All tools
735 tools available · Every tool is filed under a category, and every category page lists all of them.
Mathematics
Percentages, fractions, powers, geometry, statistics and everyday maths, each one showing the steps behind the result.
- MathematicsPercentage CalculatorThe three questions people actually ask about percentages, answered at once, including the reverse ones.
- MathematicsPercentage Change CalculatorFind the percentage increase or decrease between two values, with the absolute difference.
- MathematicsRectangle Area CalculatorArea, perimeter and diagonal of a rectangle or square.
- MathematicsScientific CalculatorType a whole expression and get the answer, with brackets, powers, roots, logs and trigonometry.
- MathematicsCircle Area CalculatorArea, circumference and diameter of a circle from its radius.
- MathematicsWhat Percentage Is X of YTurn a part and a total into a percentage share.
- MathematicsRule of Three CalculatorSolve a direct proportion: if A gives B, what does C give?
- MathematicsEquation SolverFinds the real solutions of an equation in x, including ones no formula can give you.
- MathematicsRandom Number GeneratorDraws random whole numbers in a range, with or without repeats, from a seed you can publish.
- MathematicsDerivative Calculator with StepsThe exact derivative of a function, term by term, naming the rule used at each step.
- MathematicsPythagorean Theorem CalculatorFind the hypotenuse of a right triangle from the two shorter sides.
- MathematicsIntegral Calculator with StepsThe antiderivative where the form is one that can be recognised, and the definite integral either way.
- MathematicsTriangle Area CalculatorArea of any triangle from its base and perpendicular height.
- MathematicsCylinder Volume CalculatorVolume in cubic metres and litres, plus total surface area, of a cylinder.
- MathematicsMatrix CalculatorAdd, subtract, multiply, transpose or scale matrices of any size up to twelve by twelve.
- MathematicsCurve Fitting CalculatorThe best straight line, polynomial, exponential, power or logarithmic fit to your data, by least squares.
- MathematicsFraction CalculatorAdd, subtract, multiply or divide two fractions, with the answer simplified and as a decimal.
- MathematicsRatio Calculator (simplify and share)Simplify a ratio to its smallest whole numbers and split an amount between two parts.
- MathematicsLimit CalculatorWhere a function is heading, approached from both sides, with l'Hôpital's rule applied when the form is indeterminate.
- MathematicsTriangle SolverEvery side, every angle, the area and the two radii of any triangle, from whichever three measurements you have.
- MathematicsBox Volume CalculatorVolume in cubic metres and litres, plus surface area, of a rectangular box.
- MathematicsMatrix Inverse CalculatorThe inverse of a square matrix by Gauss-Jordan elimination, with the identity check that proves it.
- MathematicsRounding CalculatorThe same number by five different rounding rules, plus significant figures and the nearest multiple.
- MathematicsDecimal to Fraction CalculatorA decimal written as a fraction in lowest terms, including recurring decimals done exactly.
- MathematicsPercentage Difference CalculatorThe symmetric percentage difference between two values, plus the change in each direction.
- MathematicsQuadratic Formula Calculator with StepsThe roots of ax² + bx + c = 0 with the discriminant worked out, the factored form and the vertex.
- MathematicsTaylor Series CalculatorThe Taylor or Maclaurin polynomial of a function, with each coefficient and how far the approximation is off.
- MathematicsFraction to Decimal ConverterTurn any fraction into a decimal number and a percentage.
- MathematicsInterpolation CalculatorA value between the points you measured, by straight line and by the polynomial through all of them.
- MathematicsComplex Number Polar Form CalculatorA complex number in both forms, with its modulus, argument, conjugate, powers by De Moivre and all its n-th roots.
- MathematicsNewton-Raphson CalculatorA root of any function by Newton's method, with the full iteration table and an honest verdict on convergence.
- MathematicsCubic Equation CalculatorThe real roots of ax³ + bx² + cx + d = 0, by Cardano or the trigonometric form, with each root checked.
- MathematicsDifferential Equation CalculatorThe exact solution of a first-order linear equation with constant coefficients, with its equilibrium and time constant.
- MathematicsExponent CalculatorRaise any number to any power, including negative and fractional exponents.
- MathematicsNumerical Integration CalculatorThe area under a curve by the trapezium, midpoint and Simpson rules, with each one's error measured.
- MathematicsPrime Factorization CalculatorBreaks a number into its prime factors, with how many divisors it has and what they add up to.
- MathematicsLaplace Transform CalculatorThe transform of a function of time, term by term, using the standard table and linearity.
- MathematicsProportional Division CalculatorAn amount split between any number of shares in proportion, with the rounding handled so the total still adds up.
- MathematicsPrime Number CheckerWhether a number is prime, and the nearest prime above and below it.
- MathematicsRoot CalculatorFind the square root, the cube root or any nth root of a positive number.
- MathematicsBisection Method CalculatorA root found by repeatedly halving an interval, with every step shown and a check that the interval brackets one.
- MathematicsTrigonometry CalculatorSine, cosine and tangent of an angle given in degrees, plus the angle in radians.
- MathematicsLaw of Sines CalculatorThe missing side or angle from the sine rule, with the common ratio and the circumradius, and a warning when two triangles fit.
- MathematicsNumber Base ConverterConvert whole numbers between binary, octal, decimal and hexadecimal.
- MathematicsLaw of Cosines CalculatorThe third side from two sides and the angle between them, or any angle from the three sides, with the substitution shown.
- MathematicsSphere Volume CalculatorVolume and surface area of a sphere from its radius.
- MathematicsFibonacci CalculatorAny term of the Fibonacci sequence, the terms around it, the running total and how close the ratio has got to the golden ratio.
- MathematicsGCD and LCM CalculatorFind the greatest common divisor and the least common multiple of two whole numbers.
- MathematicsTriangle Area from Three SidesArea, perimeter and height of a triangle when you only know the three side lengths.
- MathematicsRoman Numeral ConverterWrite any number from 1 to 3999 in Roman numerals.
- MathematicsParabola CalculatorVertex, focus, directrix, latus rectum and roots of y = ax² + bx + c.
- MathematicsPercentage Error CalculatorHow far a measurement is from the true value, in percent and in absolute terms.
- MathematicsSuccessive Percentage ChangesThe real combined effect of two percentage changes applied one after the other.
- MathematicsLinear Equation SolverSolve ax + b = c for x, with the answer substituted back as a check.
- MathematicsLogarithm CalculatorLogarithm in any base, plus the natural logarithm and the base-2 logarithm.
- MathematicsPrism Volume CalculatorVolume and surface area of a prism whose base is a regular polygon — triangular, square, hexagonal or any other.
- MathematicsDistance Between Two PointsStraight-line distance, midpoint and direction angle between two coordinates.
- MathematicsTrapezoid Area CalculatorArea of a trapezoid from its two parallel sides and its height.
- MathematicsVector Dot and Cross Product CalculatorDot product, cross product and its magnitude, the angle between two vectors and their lengths.
- MathematicsComplex Number CalculatorProduct, quotient and sum of two complex numbers, with the modulus and argument of the first.
- MathematicsVolume by Water DisplacementThe volume of an irregular object from how far the water rises, and its density if you also weigh it.
- MathematicsFactorial Calculatorn factorial, the number of digits it has and the value of (n−1)!.
- MathematicsArithmetic Sequence CalculatorThe nth term and the sum of the first n terms of an arithmetic progression.
- MathematicsHyperbola CalculatorFoci, vertices, eccentricity, asymptotes and latus rectum of x²/a² − y²/b² = 1.
- MathematicsMatrix Determinant CalculatorThe determinant of a square matrix of any size up to twelve, by Gaussian elimination.
- MathematicsRegular Polygon CalculatorArea, perimeter, apothem, circumradius and interior angle of any regular polygon.
- MathematicsScientific Notation CalculatorTurn a number written as m × 10ⁿ into ordinary decimal form.
- MathematicsCircle Sector CalculatorArc length, sector area, chord and perimeter of a slice of a circle.
- MathematicsCone Volume CalculatorVolume and slant height of a cone from its radius and vertical height.
- MathematicsSlope and Line Equation CalculatorSlope, y-intercept, angle and x-intercept of the line through two points.
- MathematicsEllipse Area and PerimeterArea, approximate perimeter and eccentricity of an ellipse from its two semi-axes.
- MathematicsGeometric Sequence CalculatorTerm n, the sum of the first n terms and the infinite sum of a geometric progression.
- MathematicsSignificant Figures RounderRound any number to a chosen number of significant figures, with the rounding error.
- MathematicsSystem of Equations CalculatorAny number of simultaneous linear equations solved by Gaussian elimination, with the answer substituted back.
- MathematicsTorus Volume CalculatorVolume, surface area and diameters of a torus from the ring radius and the tube radius.
- MathematicsAnnulus (Ring) Area CalculatorArea of a ring from the outer and inner radius, with the wall thickness.
- MathematicsPyramid Volume CalculatorVolume, base area and slant height of a rectangular-based pyramid.
Statistics
Averages, spread, correlation and the tests that say whether a difference is real — each one showing the numbers it rests on.
- StatisticsAverage CalculatorPaste a list of numbers and get the mean, median, sum, count, minimum, maximum and range.
- StatisticsWeighted Average CalculatorAverage a list of values where each one carries a different weight or coefficient.
- StatisticsStandard Deviation CalculatorHow spread out a set of numbers is, with the subtraction and the squaring laid out line by line.
- StatisticsT-Test CalculatorWhether the difference between two sets of numbers is bigger than chance would produce, with the p value and the size of the difference.
- StatisticsLinear Regression CalculatorThe straight line that fits a set of points best, with the equation, how much it explains, and a prediction.
- StatisticsMargin of Error CalculatorThe proportion your sample found, the margin of error around it, and the interval that follows — with the finite population correction when it applies.
- StatisticsCorrelation CalculatorHow closely two sets of numbers move together, by Pearson and by rank, with a confidence interval around the answer.
- StatisticsProbability CalculatorThe chance of both, either, neither or exactly one of two independent events.
- StatisticsQuartile CalculatorThe median, the quartiles, the interquartile range and the values Tukey's rule flags as outliers.
- StatisticsBayes' Theorem CalculatorWhat a positive result really means, once the rarity of the thing being tested for is taken into account.
- StatisticsChi-Square CalculatorWhether counts differ from what you expected, or whether two categories are related, with the p value and the strength of the link.
- StatisticsCombinations and Permutations CalculatorHow many ways k items can be chosen from n, with and without counting the order.
- StatisticsMean, Median and Mode CalculatorThe three averages of a set of numbers, plus the range and the count.
- StatisticsANOVA CalculatorWhether three or more groups really differ, by comparing the variation between them against the variation inside them.
- StatisticsMoving Average CalculatorSmooth a bumpy series of numbers by averaging each value with the ones before it, and see where the trend is heading.
- StatisticsStatistical Power CalculatorWhether your study is big enough to find the difference you are looking for, and how many people it would take.
- StatisticsSkewness and Kurtosis CalculatorWhich way a distribution leans and how heavy its tails are, with the standard errors that say whether either is real.
- StatisticsPermutations with Repetition CalculatorHow many arrangements are possible when things can repeat, or when the set you are rearranging already contains duplicates.
- StatisticsCoefficient of Variation CalculatorSpread as a percentage of the mean, so two things measured on different scales can be compared for variability.
- StatisticsDice Probability CalculatorChance of rolling at least one chosen face, the expected total, and the odds of all dice matching.
- StatisticsStratified Sampling CalculatorHow many people to draw from each group so that the sample mirrors the population, with the rounding handled properly.
- StatisticsBirthday Problem CalculatorChance that two of a group share a value, with the number of pairs and the group size for even odds.
- StatisticsConfidence Interval CalculatorMargin of error and confidence interval for a sample mean, with the standard error and the sample size for half the margin.
- StatisticsNormal Distribution Probability CalculatorProbability below, above and within a value on a normal curve, with the z-score and the odds of exceeding it.
- StatisticsSample Size CalculatorSample size for a survey or inspection at a chosen confidence level and margin of error.
- StatisticsProbability of At Least One CalculatorChance that an event happens at least once over repeated independent tries, with the tries needed for even odds.
- StatisticsOdds to Probability CalculatorImplied probability from odds, in decimal and fractional form, with the return on a stake.
- StatisticsZ-Score CalculatorHow many standard deviations a value sits from the mean.
- StatisticsExpected Value CalculatorExpected value of three possible outcomes, with the variance and standard deviation of the result.
- StatisticsPoisson Distribution CalculatorProbability of exactly k events, of none, and of at least one, when the average rate is known.
- StatisticsBinomial Probability CalculatorProbability of exactly k successes in n independent trials, with the expected value.
- StatisticsSample Size for Comparing Two ProportionsHow many people you need in each group to detect a difference between two rates.
- StatisticsSample Size for Comparing Two MeansHow many subjects you need per group to detect a given difference between two averages.
- StatisticsHypergeometric Probability CalculatorOdds of drawing a given number of the right things, when you draw without putting them back.
Converters
Metric, imperial and technical units converted from a single shared library, so every factor is identical across the whole site.
- ConvertersLength ConverterConvert between metres, centimetres, inches, feet, yards, miles and nine other length units.
- ConvertersTemperature ConverterConvert between Celsius, Fahrenheit, Kelvin and Rankine, with the offset handled correctly.
- ConvertersMass & Weight ConverterConvert kilograms, grams, tonnes, pounds, ounces, stones and both US and UK tons.
- ConvertersPressure ConverterConvert bar, psi, pascal, kPa, MPa, atmospheres, mmHg, torr and metres of water column.
- ConvertersVolume ConverterConvert litres, millilitres, cubic metres, gallons, pints, cups and fluid ounces.
- ConvertersSpeed ConverterConvert km/h, mph, metres per second, feet per second and knots.
- ConvertersArea ConverterConvert square metres, square feet, hectares, acres and seven other area units.
- ConvertersPower ConverterConvert watts, kilowatts, megawatts, horsepower, metric horsepower, BTU/h and tons of refrigeration.
- ConvertersEnergy ConverterConvert joules, kilojoules, kWh, calories, kilocalories, BTU and therms.
- ConvertersFuel Economy ConverterConvert L/100 km, km/L, miles per US gallon and miles per imperial gallon.
- ConvertersTime Duration ConverterConvert seconds, minutes, hours, days, weeks, months and years as durations.
- ConvertersData Storage ConverterConvert bits, bytes, kB, MB, GB, TB and the binary KiB, MiB, GiB and TiB.
- ConvertersTorque ConverterConvert newton-metres, kilogram-force metres, pound-force feet and pound-force inches.
- ConvertersForce ConverterConvert newtons, kilonewtons, kilogram-force, pound-force, tonne-force and dynes.
- ConvertersAngle ConverterConvert degrees, radians, gradians, turns, milliradians, arcminutes and arcseconds.
- ConvertersDensity ConverterConvert kg/m³, g/cm³, kg/L, t/m³, lb/ft³ and lb/in³.
- ConvertersFlow Rate ConverterConvert m³/h, m³/s, L/s, L/min, US gallons per minute and cubic feet per minute.
- ConvertersFrequency & Rotation ConverterConvert hertz, kilohertz, megahertz, revolutions per minute and radians per second.
- ConvertersData Transfer Rate ConverterConvert Mbps, MB/s, Gbit/s and the other units used for internet and disk speed.
- ConvertersAcceleration ConverterConvert m/s², g, ft/s², gal and (km/h)/s.
- ConvertersMass Flow ConverterConvert kg/s, kg/h, t/h, t/day, g/s and pounds per hour.
- ConvertersIlluminance ConverterConvert lux, foot-candles, phot and nox.
- ConvertersDynamic Viscosity ConverterConvert pascal seconds, millipascal seconds, centipoise, poise and imperial units.
- ConvertersSI Prefix ConverterConvert between metric prefixes from quetta down to quecto, including the four added in 2022.
- ConvertersPPM, PPB and Percent ConverterConvert parts per million, parts per billion, percent, per mille and milligrams per kilogram.
Electricity
Ohm's law, single and three-phase power, voltage drop, cable sizing and electronics basics.
- ElectricityOhm's Law CalculatorEnter any two of voltage, current and resistance and get the third, plus the power.
- ElectricityElectricity Cost CalculatorDaily, monthly and yearly running cost of any appliance from its wattage and hours of use.
- ElectricitySingle-Phase Power CalculatorActive, apparent and reactive power of a single-phase load from voltage, current and power factor.
- ElectricityVoltage Drop CalculatorVoltage drop in volts and percent along a copper cable, for single-phase and three-phase circuits.
- ElectricityThree-Phase Power CalculatorActive and apparent power of a balanced three-phase load, in watts, kW and kVA.
- ElectricityCable Cross-Section CalculatorMinimum conductor cross-section needed to keep voltage drop within a chosen limit.
- ElectricityMotor Full-Load Current CalculatorEstimate the full-load current of a three-phase motor from its shaft power, efficiency and power factor.
- ElectricityAWG to mm² ConverterConvert an American Wire Gauge number into conductor diameter and cross-sectional area.
- ElectricitySolar Panel Output CalculatorDaily and yearly production of a photovoltaic array, and the value of the electricity it replaces.
- ElectricitySeries and Parallel Resistor CalculatorEquivalent resistance of two resistors connected in series and in parallel.
- ElectricitykVA to Amps CalculatorCurrent drawn by a load rated in kVA, for single-phase and three-phase supplies.
- ElectricityRLC Impedance and Resonance CalculatorImpedance, phase angle, resonant frequency, Q factor and bandwidth for a series or parallel RLC circuit.
- ElectricityLED Series Resistor CalculatorResistor value and power needed to run an LED safely from a given supply.
- ElectricityBattery Life CalculatorEstimate how long a battery will last from its capacity and the current drawn.
- ElectricitySolar Battery Bank CalculatorBattery capacity in amp-hours for a daily consumption and a chosen number of cloudy days.
- ElectricityBattery Charging Time CalculatorHow long a battery takes to charge, with the charge rate expressed as a C-rate.
- ElectricityWire Resistance CalculatorResistance of a conductor from its length, cross-section and resistivity.
- ElectricityRMS CalculatorThe root mean square of a waveform or a list of readings, with peak, average, form factor and crest factor.
- ElectricityVoltage Divider CalculatorOutput voltage, current and power dissipation of a two-resistor divider.
- ElectricityInverter Size CalculatorInverter rating for a given load, with the DC current it will draw at full load and on surge.
- ElectricityGenerator Size CalculatorThe generator rating needed for a given running load plus the surge of the largest motor, in W and kVA.
- ElectricityLED Strip Power Supply CalculatorTotal wattage, current and recommended power supply size for a run of LED strip.
- ElectricityPower Factor Correction CalculatorCapacitor bank size in kvar needed to raise the power factor from one value to another.
- ElectricityRoom Lighting CalculatorTotal lumens and number of luminaires needed to reach a target illuminance.
- ElectricitySpeaker Impedance CalculatorThe load an amplifier sees from several drivers wired in series, in parallel or series-parallel, with the current and voltage.
- ElectricityAmplifier Power CalculatorHow many watts a speaker needs to reach a given loudness at a given distance, with the headroom counted in.
- ElectricityCable Power Loss CalculatorPower wasted as heat in a cable run, and what that waste costs over a year.
- ElectricityInductor Combination CalculatorTotal inductance of any number of coils in series or parallel, with the other arrangement shown alongside.
- ElectricityMotor Efficiency CalculatorEfficiency, losses and the yearly cost of those losses for a motor.
- ElectricityBattery Pack Configuration CalculatorVoltage, capacity and energy of a series-parallel pack, with the runtime and current at a given load.
- ElectricitySeries and Parallel Capacitor CalculatorEquivalent capacitance of two capacitors in parallel and in series.
- ElectricityPassive Crossover CalculatorCapacitor and inductor values for a first or second order passive crossover, from the crossover frequency and the driver impedances.
- ElectricityAudio Level ConverterConvert between dBu, dBV, volts and dBFS, with the alignment level you choose, plus peak and peak-to-peak voltage.
- ElectricityLumens to Watts CalculatorLuminous efficacy of a lamp, the incandescent equivalent and the yearly running cost.
- ElectricityPV String Sizing CalculatorMaximum modules per string from the cold open-circuit voltage, with the minimum for the MPPT window.
- ElectricityInductive and Capacitive Reactance CalculatorReactance of a coil and a capacitor at a given frequency, plus the resonant frequency of the pair.
- ElectricityCable Ampacity Derating CalculatorCorrected current-carrying capacity of a cable, and the table value a design current needs.
- ElectricityAudio Headroom CalculatorHeadroom, crest factor, the noise floor of a given bit depth and how much of the available range a recording actually uses.
- ElectricityTransformer Turns Ratio CalculatorVoltage ratio and secondary turns of a transformer from the primary and secondary voltages.
- ElectricityCapacitor Energy CalculatorEnergy stored in a capacitor and the charge it holds, from capacitance and voltage.
- ElectricityRC Time Constant and Filter CalculatorTime constant, settling time and cut-off frequency of a resistor-capacitor pair.
- ElectricityThree-Phase Fault Current CalculatorProspective short-circuit current at a transformer's terminals, with the peak current and the fault level.
- ElectricityOp-Amp Gain CalculatorGain of an op-amp stage in both configurations, in ratio and decibels, with the output and the bandwidth left.
- ElectricityAntenna Length CalculatorQuarter-wave, half-wave and full-wave lengths for a frequency, with the dipole half-length.
- ElectricityCable Short-Circuit Withstand CalculatorMinimum cable cross-section for a fault current and clearing time, and how long a given cable survives it.
- ElectricitySolar Panel Payback CalculatorSee how long a solar system takes to pay for itself, with your own tariffs and panel degradation.
- ElectricityStar-Delta (Y-Δ) Conversion CalculatorEquivalent star resistances from three delta resistances, and back again.
- ElectricityWheatstone Bridge CalculatorBridge output voltage, the resistance that would balance it, and the sensitivity in millivolts per ohm.
- ElectricityUPS and Battery Backup Runtime CalculatorWork out how long a battery bank will carry a given load through a power cut.
Mechanics
Force, torque, rotation, gear ratios, belt speed, stress and the mechanical calculations used on the shop floor.
- MechanicsTorque CalculatorTorque from a force applied at a distance, in N·m, kgf·m and lbf·ft.
- MechanicsForce Calculator (F = m·a)Force from mass and acceleration, plus the weight of that mass under standard gravity.
- MechanicsMechanical Power from Torque and SpeedShaft power in watts, kW and horsepower from torque and rotational speed.
- MechanicsGear Ratio CalculatorGear ratio, output speed and output torque from the number of teeth on each gear.
- MechanicsStress CalculatorDirect stress from a force acting on a cross-section, in MPa, psi and kgf/cm².
- MechanicsCutting Speed and RPM CalculatorConvert between surface cutting speed and spindle speed for a given tool or workpiece diameter.
- MechanicsPulley Speed CalculatorDriven pulley speed, drive ratio and belt linear speed from two pulley diameters.
- MechanicsBolt Tightening Torque CalculatorTightening torque needed to reach a target bolt preload, using the nut-factor method.
- MechanicsMaterial Weight CalculatorWeight of a rectangular bar or plate, with weight per metre and per square metre.
- MechanicsHydraulic Cylinder Force CalculatorPush and pull force of a hydraulic cylinder from bore, rod diameter and working pressure.
- MechanicsTapping Drill Size CalculatorDrill diameter for a metric thread at a chosen engagement, plus the clearance and pitch diameters.
- MechanicsBeam Deflection CalculatorSag of a simply supported beam with a central point load, and the span-to-deflection ratio.
- MechanicsBelt Length CalculatorApproximate belt length and wrap angle on the small pulley from two diameters and centre distance.
- MechanicsElastic Elongation CalculatorHow much a bar stretches under load, with the resulting strain and stress.
- MechanicsMachining Feed Rate CalculatorTable feed in mm/min from spindle speed, feed per tooth and number of teeth.
- MechanicsLever CalculatorOutput force and mechanical advantage of a lever from the two arm lengths.
- MechanicsBearing Life (L10) CalculatorBasic rating life of a rolling bearing in hours, revolutions and years of continuous running.
- MechanicsSling Angle Load CalculatorTension in each sling leg at a given angle from vertical, with the angle factor and the sideways pull.
- MechanicsSpring Rate CalculatorSpring stiffness in N/m and N/mm from a known force and deflection, with the stored energy.
- MechanicsShaft Torsion Stress CalculatorShear stress and section modulus of a solid round shaft under torque.
- MechanicsEuler Buckling Load CalculatorCritical buckling load of a column, with the stress at that load and the slenderness ratio.
- MechanicsGear Module and Centre Distance CalculatorPitch diameter, outside diameter, circular pitch and the centre distance of a gear pair.
- MechanicsPump and Fan Affinity Laws CalculatorFlow, head and power at a new speed, with the power saved and what that saves in a year.
- MechanicsSecond Moment of Area CalculatorI and W for a solid rectangular section and a solid round section.
- MechanicsCentrifugal Force CalculatorForce on a rotating mass, in newtons, kilogram-force and g.
- MechanicsHelical Compression Spring CalculatorSpring rate, deflection under load, spring index, Wahl factor and the corrected shear stress.
- MechanicsHydraulic Pump Flow CalculatorFlow delivered by a pump and the drive power it needs at a working pressure.
- MechanicsSheet Metal Bend Allowance CalculatorBend allowance and total flat length for a sheet metal part before folding.
- MechanicsFillet Weld Size CalculatorThroat and leg size a fillet weld needs for a load, and the capacity of a weld you already have.
- MechanicsNPSH Available CalculatorNet positive suction head available at a pump, the margin over what it requires, and the highest suction lift it allows.
- MechanicsHydraulic Motor Torque CalculatorTorque, shaft speed and power of a hydraulic motor from pressure, displacement and flow.
- MechanicsPlanetary Gear Ratio CalculatorThe three ratios an epicyclic set can give depending on which member is held, and the planet tooth count.
- MechanicsBeam Natural Frequency CalculatorFirst and second natural frequencies of a simply supported beam, with the static deflection and the deflection-based estimate.
- MechanicsFlywheel Energy CalculatorStored energy, moment of inertia and rim speed of a solid disc flywheel.
- MechanicsLead Screw Torque CalculatorTorque to raise and to lower a load on a power screw, with the efficiency and the drive power.
- MechanicsOrifice Plate Flow CalculatorFlow rate through an orifice plate from the differential pressure, with the beta ratio and velocities.
- MechanicsFatigue Life Calculator (Basquin)Cycles and running hours to fatigue failure at a stress amplitude, with the stress giving a million cycles.
- MechanicsMachining Time CalculatorCutting time for a turning pass, with spindle speed, feed rate in mm/min and material removal rate.
- MechanicsMean Piston Speed CalculatorAverage piston speed at a given engine speed, and the rpm that reaches 20 m/s.
- MechanicsPump Power CalculatorShaft power a pump needs for a given flow, head and efficiency.
- MechanicsPipe Pressure Rating Calculator (Barlow)Working or burst pressure of a pipe from outside diameter, wall thickness and allowable stress.
- MechanicsBolt Shear Capacity CalculatorDesign shear and tension capacity of a bolt from its stress area, grade and the number of shear planes.
- MechanicsPress Brake Tonnage CalculatorBending force in kN and tonnes for air bending, plus minimum flange and the natural inside radius for the die.
- MechanicsTurning Surface Roughness CalculatorTheoretical Ra and Rz from feed and tool nose radius, and the feed needed to hit a target roughness.
Engineering
Industrial and process engineering: OEE, takt time, capacity, efficiency, tolerances and unit-heavy technical work.
- EngineeringOEE CalculatorOverall equipment effectiveness with its three factors: availability, performance and quality.
- EngineeringTakt Time CalculatorThe pace a line must run at to meet customer demand, in seconds per unit.
- EngineeringProduction Capacity CalculatorUnits per shift, per hour and per week from cycle time, efficiency and machine count.
- EngineeringCost Per Unit CalculatorUnit cost of a batch, showing how much of it is fixed cost spread over the quantity.
- EngineeringDowntime Cost CalculatorThe cost of a stoppage, counting lost margin and the fixed costs that keep running.
- EngineeringFirst Pass Yield CalculatorShare of units that pass without rework, alongside the final yield.
- EngineeringScrap Cost CalculatorWhat a scrap rate costs per period and per year.
- EngineeringLabour Productivity CalculatorUnits per person-hour, units per person and the labour minutes each unit consumes.
- EngineeringDPMO CalculatorDefects per million opportunities, with defects per unit and yield.
- EngineeringCp and Cpk CalculatorProcess capability indices from the specification limits, the mean and the standard deviation.
- EngineeringAir Changes Per Hour CalculatorAir changes per hour for a room, the flow a target rate needs, and the time for one complete change.
- EngineeringMTBF and Availability CalculatorMean time between failures, availability and total downtime from run hours and failure count.
- EngineeringLine Balancing and Takt Time CalculatorTakt time, theoretical number of workstations and balance efficiency of an assembly line.
- EngineeringElectricity CO₂ Emissions CalculatorCarbon dioxide from electricity use, with comparisons to trees and car kilometres.
- EngineeringCapacity Utilisation CalculatorUtilisation rate, spare capacity and how fixed costs per unit change when you fill the plant.
- EngineeringEconomic Order Quantity CalculatorThe order size that balances ordering costs against holding costs, with the order frequency.
- EngineeringStock Cover CalculatorDays of stock remaining, the reorder point for a lead time, and how many days of margin are left.
- EngineeringDuct Velocity and Sizing CalculatorAir velocity in a rectangular duct, its equivalent round diameter, and the size a target velocity needs.
- EngineeringEnergy Cost per Part CalculatorElectricity consumed and paid for by each part produced, and the yearly total.
- EngineeringPsychrometric CalculatorHumidity ratio, enthalpy, saturation pressure and density of moist air at a given state.
- EngineeringInventory Turnover CalculatorHow many times a year stock is sold and replaced, and how many days of stock that represents.
- EngineeringLMTD Heat Exchanger CalculatorLog mean temperature difference, the heat duty it gives, and the area a 100 kW duty would need.
- EngineeringStaffing Requirement CalculatorHeadcount needed for a workload, allowing for real efficiency and absence.
- EngineeringControl Chart Limits CalculatorUpper and lower control and warning limits for a control chart, from the process mean and standard deviation.
- EngineeringDegree Days CalculatorHeating and cooling degree days for a period, and the energy a building of a given fabric would need.
- EngineeringDittus-Boelter Heat Transfer CalculatorNusselt number and convective heat transfer coefficient for turbulent flow inside a tube.
- EngineeringHeat Exchanger Effectiveness (NTU) CalculatorEffectiveness, NTU, capacity ratio and duty of a counterflow heat exchanger.
- EngineeringPneumatic Cylinder Air Consumption CalculatorFree air consumption of a pneumatic cylinder in NL/min and m³/h, plus the push force it develops.
- EngineeringFin Efficiency CalculatorEfficiency and heat output of a straight rectangular fin from its thickness, length, material and air-side coefficient.
- EngineeringAir Receiver Size CalculatorThe receiver volume needed to cover a given air demand for a given time within an allowed pressure drop.
Construction & DIY
Concrete, paint, tiles, flooring, slopes, excavation and material quantities for real building jobs.
- Construction & DIYConcrete Volume CalculatorCubic metres and tonnes of concrete needed for a slab, with a waste allowance.
- Construction & DIYPaint CalculatorLitres of paint needed for a given wall area, number of coats and coverage rate.
- Construction & DIYTile CalculatorHow many tiles you need for an area, with a cutting allowance.
- Construction & DIYSlope and Gradient CalculatorSlope as a percentage, an angle, a ratio and the sloping length.
- Construction & DIYFlooring CalculatorHow many packs of flooring to buy for a room, including waste.
- Construction & DIYRoom Wall Area CalculatorWall area, floor area, perimeter and volume of a rectangular room.
- Construction & DIYGravel and Aggregate CalculatorTonnes and cubic metres of gravel for a given area and depth, with the cost.
- Construction & DIYBrick CalculatorNumber of bricks or blocks for a wall area, counting the mortar joint.
- Construction & DIYRoof Pitch CalculatorRoof angle, pitch percentage, rafter length and roof area per metre of length.
- Construction & DIYDrywall CalculatorSheets, screws, joint tape and compound for a plasterboard job, from the area and the sheet size.
- Construction & DIYExcavation Volume CalculatorTrench volume in place, loose spoil volume after bulking, weight and truck loads.
- Construction & DIYConcrete Mix CalculatorCement bags, sand and gravel for a given volume and mix ratio.
- Construction & DIYStair CalculatorNumber of steps, exact riser height, total run and the Blondel comfort value.
- Construction & DIYLand Plot Area Calculator (four sides)Area of an irregular four-sided plot from its four sides and one diagonal, in square metres, hectares and acres.
- Construction & DIYHeat Loss Through a Wall CalculatorHeat lost through a surface, the daily energy it costs and the price of that energy.
- Construction & DIYSwimming Pool Volume CalculatorPool volume in cubic metres and litres, plus the filtration turnover time.
- Construction & DIYWallpaper CalculatorHow many rolls of wallpaper a room needs, counted in full drops.
- Construction & DIYDrawing Scale ConverterTurn a measurement taken off a scale drawing into the real-world size.
- Construction & DIYPipe Volume and Weight CalculatorLitres per metre, total volume, pipe weight and the weight of what is inside, from the outside diameter and the wall thickness.
- Construction & DIYPlaster and Render CalculatorBags of plaster or render for a wall area at a given thickness.
- Construction & DIYRainwater Harvesting CalculatorRainwater you can collect from a roof in a year, and the average per day.
- Construction & DIYSuspended Ceiling CalculatorPanels, grid runners, edge trim and hangers for a suspended ceiling, from the room size and the panel size.
- Construction & DIYColumn Concrete CalculatorConcrete volume and mass, formwork area, main bars and stirrups for rectangular columns.
- Construction & DIYRoof Tiles CalculatorNumber of tiles for a pitched roof, from the plan dimensions and the pitch angle.
- Construction & DIYU-Value and Insulation CalculatorThermal transmittance and resistance of an insulation layer, from thickness and conductivity.
- Construction & DIYBackfill CalculatorHow much fill a trench needs once the pipe or structure is in, in loose volume, tonnes and truck loads.
- Construction & DIYRebar Weight CalculatorWeight of reinforcement bars from diameter, length and quantity.
- Construction & DIYShelf Sag CalculatorSag of a loaded shelf, its stiffness ratio, the load for a 1:250 limit and the span that would halve the sag.
- Construction & DIYBoard Feet CalculatorBoard feet in a piece of timber, the total for a batch, the volume in cubic metres, cost and rough weight.
- Construction & DIYTile Grout CalculatorKilograms of grout for a tiled area, from tile size, joint width and tile thickness.
- Construction & DIYWaterproofing CalculatorMembrane area, rolls, primer and litres of liquid waterproofing, including the upstand at the walls.
- Construction & DIYDecking Boards CalculatorHow many deck boards a terrace needs, plus total linear metres and joist count.
- Construction & DIYRadiator Output CalculatorThe real heat output of a radiator at your actual flow and return temperatures, against its catalogue rating.
- Construction & DIYRamp Length CalculatorHorizontal run, sloping length and angle of a ramp for a given rise and gradient.
- Construction & DIYWelded Mesh CalculatorSheets, mass per square metre and total weight of reinforcement mesh, with the lap between sheets taken off.
- Construction & DIYWind Load CalculatorDynamic wind pressure and the force on a flat surface, with the overturning moment about its base.
- Construction & DIYDrainage Fall CalculatorTotal fall over a pipe run for a given gradient, in millimetres, percent and mm per metre.
- Construction & DIYUnderfloor Heating Pipe CalculatorMetres of pipe and number of loops for an underfloor heating circuit.
- Construction & DIYFence Posts CalculatorPosts, panels, the exact spacing that results and the concrete needed to set them.
- Construction & DIYGate CalculatorLeaf width, pickets, frame and brace lengths, weight and the load each hinge carries.
- Construction & DIYMulti-Layer Wall R-Value CalculatorTotal thermal resistance and U-value of a three-layer wall, and how much of it the insulation contributes.
- Construction & DIYSkirting Board CalculatorMetres of skirting and number of lengths needed for a room, allowing for doorways.
- Construction & DIYHorizontal Cylindrical Tank Volume CalculatorLitres in a horizontal round tank from the depth of liquid, plus the percentage full.
- Construction & DIYManning Open Channel Flow CalculatorFlow and velocity in a rectangular open channel, with the hydraulic radius and wetted area.
- Construction & DIYWood Movement CalculatorHow much a board changes width as its moisture content changes, with the gap to allow.
- Construction & DIYConcrete Block CalculatorHow many blocks a wall takes, from its area and the block size you are using.
- Construction & DIYCable Sag CalculatorSag, end tension and developed length of a cable or wire strung between two supports at the same height.
Finance
Interest, loans, savings, inflation, margin, markup and VAT. Informational calculators, not financial advice.
- FinanceCompound Interest CalculatorFuture value of savings with compound interest and optional monthly contributions.
- FinanceDiscount CalculatorFinal price after a percentage discount, and how much you save.
- FinanceLoan Payment CalculatorMonthly instalment, total paid and total interest on a loan repaid in equal payments.
- FinanceVAT CalculatorAdd VAT to a net price and remove VAT from a gross price, both at once.
- FinanceInflation CalculatorWhat an amount of money will be worth in real terms after years of inflation, and what it would cost.
- FinanceProfit Margin CalculatorGross margin, profit and the equivalent markup from cost and selling price.
- FinanceSimple Interest CalculatorInterest and final amount when interest is not compounded.
- FinanceROI CalculatorReturn on investment as a total percentage and as an annualised rate.
- FinanceSavings Goal CalculatorHow much to put aside each month to reach a target amount by a chosen date.
- FinanceAmortisation Schedule CalculatorThe payment, and a year-by-year table of how much goes to interest, how much to capital, and what is left owing.
- FinanceMarkup CalculatorSelling price from a cost price and a markup percentage, with the resulting margin.
- FinanceHow Much Can I Borrow CalculatorMaximum loan from an income, a share of income you accept as an instalment, a rate and a term.
- FinanceMonthly Budget CalculatorAdd up where the money goes, see what is left, and find out what share of your income you actually keep.
- FinanceBreak-Even Point CalculatorHow many units you must sell to cover fixed costs, and the revenue that represents.
- FinanceIRR CalculatorThe internal rate of return of any series of cash flows, with the net present value and a warning when the answer is not unique.
- FinanceCAGR CalculatorThe steady yearly rate that turns one figure into another over a number of years, which is not the total growth divided by the years.
- FinanceReal Return CalculatorWhat an investment actually earns once inflation is taken out, and why subtracting the two numbers is not the same thing.
- FinanceAnnuity CalculatorWhat a stream of equal payments is worth today and what it adds up to at the end, paid at the start or the end of each period.
- FinanceFIRE CalculatorThe capital that would cover a year of your spending indefinitely, how far off it is, and how long the current pace takes to get there.
- FinanceOutstanding Loan Balance CalculatorHow much of a loan is still owed after a number of instalments, and how much capital has been repaid.
- FinanceTravel Budget CalculatorWhat a trip will cost in total, per person, per day and per person per day, with a margin for what always comes up.
- FinancePortfolio Return CalculatorThe weighted return of a whole portfolio, with each holding's weight, its contribution, and how concentrated the whole thing is.
- FinanceYield to Maturity CalculatorWhat a bond really returns if held to the end, counting both the coupons and the gain or loss against face value.
- FinanceCredit Card Payoff CalculatorMonths to clear a credit card balance at a fixed monthly payment, and the interest it costs.
- FinanceInterest Rate Conversion CalculatorTurn a rate quoted for one period into the equivalent for any other — monthly, annual, nominal, effective or continuous.
- Finance50/30/20 Budget CalculatorMonthly budget split into needs, wants and savings, with the shares adjustable.
- FinanceMonte Carlo Investment SimulatorA thousand possible futures for the same savings plan, showing the range of outcomes rather than a single false-precise number.
- FinanceBeta CalculatorHow much an investment moves with the market, with alpha, correlation and the R² that says whether the beta means anything.
- FinanceDoubling Time Calculator (Rule of 72)How long money takes to double at a given rate, exactly and by the rule of 72.
- FinanceMortgage Overpayment CalculatorMonths cut from a mortgage and interest saved by paying extra each month.
- FinanceDollar Cost Averaging CalculatorThe price you really paid when you invested the same amount at different prices, against the plain average of those prices.
- FinanceSalary Increase CalculatorNew salary after a raise, the yearly gain and whether the raise beats inflation.
- FinanceDeclining Balance Depreciation CalculatorWhat something is worth after a number of years when it loses the same percentage of its remaining value every year.
- FinanceEffective Annual Rate CalculatorConvert a nominal annual rate with periodic compounding into the true effective annual rate.
- FinanceRetirement Capital CalculatorProjected capital from current savings plus monthly contributions, and what it could pay out.
- FinanceDiscounted Payback Period CalculatorHow long an investment takes to pay for itself once future money is discounted, next to the plain payback for comparison.
- FinanceNet Present Value (NPV) CalculatorNet present value of a constant annual cash flow against an upfront investment.
- FinancePrice Per Square Metre CalculatorPrice per square metre with and without purchase costs, and how it compares with a reference for the area.
- FinanceEmergency Fund CalculatorHow large an emergency fund should be, the gap to it and how long it takes to fill.
- FinanceRental Yield CalculatorGross, net and vacancy-adjusted rental yield, the income after costs and the payback period.
- FinanceBinomial Option Pricing CalculatorOption value from a Cox-Ross-Rubinstein tree, including American early exercise, with Black-Scholes alongside for comparison.
- FinancePayback Period CalculatorHow long an investment takes to pay for itself, after yearly running costs.
- FinancePresent Value CalculatorWhat a future amount of money is worth today at a given discount rate.
- FinanceSavings Withdrawal CalculatorMonthly income a lump sum can pay out over a fixed number of years before it runs out.
- FinanceStraight-Line Depreciation CalculatorAnnual depreciation, book value after n years and the total written off.
- FinancePerpetuity CalculatorWhat an income that never stops is worth today, with or without growth, and what capital a given income needs.
- FinanceDividend Yield CalculatorDividend yield, annual income from a holding, and the payout ratio.
- FinanceLate Payment Interest CalculatorInterest on an overdue invoice, the daily rate and the total now due.
- FinanceBond Price CalculatorPrice of a bond from its yield, with the current yield, the price as a percentage of par and the effect of a 1 % yield rise.
- FinanceReal Return After Tax and Inflation CalculatorWhat a nominal return is actually worth once tax and inflation have both taken their share.
- FinanceSharpe Ratio CalculatorSharpe ratio of a portfolio, annualised from any period, with the excess return and the return a ratio of 1 would need.
- FinanceBlack-Scholes Option Price CalculatorEuropean call option price, with d₁, d₂, the discounted strike and the intrinsic value.
- FinanceCurrency Converter (Your Own Rate)Convert an amount at a rate you enter, and see what the margin really costs you.
- FinanceWACC CalculatorWeighted average cost of capital, with the equity weight, the after-tax cost of debt, gearing and the tax shield.
- FinanceCAPM Cost of Equity CalculatorRequired return on equity from the risk-free rate, beta and the market return.
- FinanceNPV Calculator for Uneven Cash FlowsDiscount a whole series of cash flows, one figure per period, and see what the project is worth today.
- FinanceKelly Criterion CalculatorThe fraction of a bankroll to stake for maximum long-run growth, with half-Kelly and the break-even probability.
- FinanceBond Duration and Convexity CalculatorMacaulay and modified duration plus convexity, summed from the actual cash flows, with what a one-point rate move does to the price.
Physics
Motion, forces, energy, momentum, rotation, waves, light and radioactivity — the physics formulas used in school and at work.
- PhysicsSpeed, Distance and Time CalculatorFill in any two of speed, distance and time and get the third.
- PhysicsKinematics CalculatorGive any three of starting speed, final speed, acceleration, time and distance, and the other two come out.
- PhysicsAcceleration CalculatorAverage acceleration from a change in speed over a time, with the distance covered.
- PhysicsFriction Force CalculatorThe force friction is actually applying, what it takes to break an object free, and how far it slides to a stop.
- PhysicsInclined Plane CalculatorThe forces on a slope: what pulls down it, what presses into it, whether it slides, and the force to hold or raise it.
- PhysicsCollision CalculatorThe speeds after a collision, elastic, inelastic or anywhere in between, with the energy that survives and the energy that does not.
- PhysicsKinetic Energy CalculatorEnergy of a moving object, plus the height it would have to fall to gain the same energy.
- PhysicsRope Tension CalculatorThe tension in a rope for the four cases that come up: hanging, in a lift, over a pulley, and shared between two ropes.
- PhysicsMoment of Inertia CalculatorRotational inertia for the standard shapes, with the parallel axis theorem, radius of gyration and stored energy.
- PhysicsFree Fall CalculatorDistance fallen and speed reached after a given time of free fall.
- PhysicsCentre of Mass CalculatorThe balance point of several masses along a line or across a plane, with each one's share of the total.
- PhysicsWork and Power CalculatorWork done by a force over a distance, and the power that implies over a time.
- PhysicsSpherical Mirror CalculatorWhere a concave or convex mirror puts the image, how big it is, and whether it is real, virtual, upright or inverted.
- PhysicsPotential Energy CalculatorGravitational potential energy at a height, and the speed it converts into.
- PhysicsSound Level and Distance CalculatorSound level at a new distance, the intensity and pressure behind it, and the level from several identical sources.
- PhysicsTime Dilation and Length Contraction CalculatorLorentz factor at a given fraction of light speed, with the stretched time, the shortened length and the kinetic energy.
- PhysicsHalf-Life CalculatorQuantity remaining after radioactive decay, the number of half-lives elapsed and the decay constant.
- PhysicsHooke's Law Spring CalculatorForce in a spring at a given extension, the energy stored, the sag under a mass and the natural frequency.
- PhysicsWavelength CalculatorWavelength from frequency and wave speed, including the quarter-wave length.
- PhysicsMass-Energy Equivalence CalculatorEnergy locked in a given mass, expressed in joules, kilowatt-hours and tonnes of TNT.
- PhysicsMomentum and Impulse CalculatorMomentum of a moving mass, and the force needed to change it in a given time.
- PhysicsProjectile Range CalculatorHow far, how high and for how long a projectile travels, from launch speed and angle.
- PhysicsCoulomb's Law CalculatorElectrostatic force between two point charges, the field of the first, and their potential energy.
- PhysicsGravitational Force CalculatorAttraction between two masses and the acceleration the larger one produces.
- PhysicsBanked Curve Speed CalculatorDesign speed of a banked curve with no friction, the maximum speed with grip, and the flat-road limit.
- PhysicsDoppler Effect CalculatorFrequency heard as a source approaches and as it recedes, with the shift in hertz and semitones.
- PhysicsThin Lens Equation CalculatorImage distance, magnification and image height for a thin lens, plus its optical power in dioptres.
- PhysicsEscape Velocity CalculatorSpeed needed to escape a body's gravity, and the speed needed to orbit it at the surface.
- PhysicsSnell's Law Refraction CalculatorAngle of refraction between two media, the critical angle and the speed of light in each.
- PhysicsLorentz Force CalculatorMagnetic force on a moving charge, the radius it curves through and its cyclotron frequency.
- PhysicsPhoton Energy CalculatorEnergy of a photon from its wavelength, in electronvolts, attojoules and kilojoules per mole.
- PhysicsSpeed of Sound CalculatorSpeed of sound in air at a given temperature, the travel time over a distance and the echo rule.
- PhysicsAngular Momentum CalculatorAngular momentum and rotational energy, and the new speed if the moment of inertia changes.
- PhysicsPendulum Period CalculatorSwing period and frequency of a simple pendulum, plus the length for a one-second period.
- PhysicsForce on a Current-Carrying Wire CalculatorForce a magnetic field exerts on a wire carrying current, in total and per metre.
- PhysicsStanding Wave and Harmonics CalculatorResonant frequency of a string or open pipe at a chosen harmonic, and the closed-pipe frequency alongside.
- PhysicsBeat Frequency and Tuning CalculatorBeat rate between two close frequencies, the time between beats, and the interval in cents.
- PhysicsDe Broglie Wavelength CalculatorThe matter wavelength of a particle from its mass and speed, in metres, nanometres and picometres.
Heat & Fluids
Pressure, buoyancy, pipe flow and head loss, specific and latent heat, conduction, convection, radiation and the gas laws — the two halves of thermofluids, each stating the law it comes from.
- Heat & FluidsDensity CalculatorFill in any two of mass, volume and density and get the third.
- Heat & FluidsHeat Conduction CalculatorHeat flow through a solid layer by Fourier's law, with the thermal resistance and what it costs over a day and a year.
- Heat & FluidsLatent Heat CalculatorThe energy needed to melt or boil something, and how long a given heater would take to do it.
- Heat & FluidsPipe Flow Velocity CalculatorFlow velocity inside a pipe from the flow rate and the internal diameter.
- Heat & FluidsHeat Energy CalculatorEnergy needed to change the temperature of a mass, in megajoules and kilowatt-hours.
- Heat & FluidsContinuity Equation CalculatorHow fast a fluid speeds up when the pipe narrows, with the flow rate, the areas and the pressure it trades away.
- Heat & FluidsConvection Heat Transfer CalculatorHeat carried away from a surface by air or water, from Newton's law of cooling, with the area or coefficient you would need.
- Heat & FluidsFirst Law of Thermodynamics CalculatorThe change in internal energy from the heat going in and the work coming out, with the temperature change it implies.
- Heat & FluidsHydrostatic Pressure CalculatorPressure at a depth in a liquid, as gauge pressure and as absolute pressure.
- Heat & FluidsReynolds Number CalculatorReynolds number for pipe flow, the critical speed and an estimated friction factor.
- Heat & FluidsThermal Expansion CalculatorHow much a bar, rail or pipe grows when its temperature rises.
- Heat & FluidsBernoulli Equation CalculatorDownstream pressure from upstream conditions, with the velocity and height contributions shown separately.
- Heat & FluidsDarcy-Weisbach Head Loss CalculatorFriction head loss and pressure drop along a pipe, with the flow rate and the power it costs.
- Heat & FluidsCarnot Efficiency CalculatorMaximum theoretical efficiency of a heat engine between two temperatures, plus the ideal COP of a fridge and a heat pump.
- Heat & FluidsTerminal Velocity CalculatorSteady falling speed at which air resistance exactly balances weight.
- Heat & FluidsBuoyancy CalculatorUpthrust on a submerged body, the net weight in the fluid and how much of it floats below the surface.
- Heat & FluidsIdeal Gas Law CalculatorAmount of substance from pressure, volume and temperature, with the molar volume.
- Heat & FluidsStefan-Boltzmann Radiation CalculatorHeat radiated by a hot surface, the net loss to its surroundings and the wavelength it peaks at.
- Heat & FluidsWien's Displacement Law CalculatorWavelength at which a hot body radiates most strongly, with the matching frequency and photon energy.
- Heat & FluidsPipe Friction Factor CalculatorThe Darcy friction factor from pipe diameter, wall roughness and Reynolds number, using the Swamee-Jain equation.
- Heat & FluidsHazen-Williams Head Loss CalculatorHead loss, pressure drop and velocity in a water pipe from flow rate, diameter, length and the C roughness coefficient.
- Heat & FluidsCOP, EER and kW/ton ConverterConvert coefficient of performance, energy efficiency ratio and kilowatts per ton of refrigeration.
- Heat & FluidsThermal Conductivity ConverterConvert W/(m·K), BTU/(h·ft·°F), BTU·in/(h·ft²·°F) and kcal/(h·m·°C).
- Heat & FluidsCooling Time Calculator (Lumped Capacitance)Temperature of a part after a given time in air or a bath, plus its thermal time constant and Biot number.
- Heat & FluidsHeat Transfer Coefficient ConverterConvert W/(m²·K), BTU/(h·ft²·°F) and kcal/(h·m²·°C).
Chemistry
Concentrations, dilutions, gas laws, pH and buffers, reaction yields and rates, each one stating the law it comes from.
- ChemistrySolution Dilution Calculator (C₁V₁ = C₂V₂)Volume of stock solution needed to make a given volume at a lower concentration.
- ChemistryMolar Mass CalculatorType a chemical formula and get its molar mass, with a breakdown of what it is made of.
- ChemistryPercent Yield CalculatorReaction yield as a percentage of the theoretical maximum, with the loss and the moles involved.
- ChemistryTitration CalculatorUnknown concentration from a titration, plus the moles and the mass of analyte in the sample.
- ChemistryPPM Concentration CalculatorParts per million converted to mg/L, percent, ppb, total mass and molarity.
- ChemistryLimiting Reagent CalculatorWhich of two reagents runs out first, how much of the other is left over, and how far the reaction goes.
- ChemistryMass Percent Concentration CalculatorPercent by mass of a solution, converted to grams per litre, molarity and parts per million.
- ChemistryHenderson-Hasselbalch Buffer CalculatorpH of a buffer from its pKa and the ratio of conjugate base to weak acid.
- ChemistryCombined Gas Law CalculatorNew volume of a fixed amount of gas after a change of pressure and temperature, with the ratio and the moles present.
- ChemistryFreezing Point Depression CalculatorHow far a dissolved substance lowers the freezing point of a solvent.
- ChemistryMolality CalculatorMoles of solute per kilogram of solvent, with the mole fraction and mass percent.
- ChemistryBeer-Lambert Law CalculatorAbsorbance from concentration and path length, the transmittance it corresponds to, and the concentration giving A = 1.
- ChemistryMolarity CalculatorMolar concentration of a solution from the mass of solute, its molar mass and the volume.
- ChemistryOsmotic Pressure CalculatorOsmotic pressure of a solution in kilopascals, atmospheres and bar, with its osmolarity.
- ChemistryBoiling Point Elevation CalculatorHow far a dissolved substance raises the boiling point of a solvent.
- ChemistryFirst-Order Kinetics CalculatorConcentration remaining after a given time, the half-life and the time to reach 90 % conversion.
- ChemistrypH CalculatorpH and pOH from the hydrogen ion concentration of a solution.
- ChemistryArrhenius Equation CalculatorRate constant at two temperatures, how much faster the reaction gets, and the ten-degree factor.
- ChemistryFaraday Electrolysis CalculatorMass deposited or dissolved by a current over time, with the charge passed and the moles involved.
- ChemistryNernst Equation CalculatorCell potential away from standard conditions, the slope per decade, the Gibbs energy and the equilibrium constant.
- ChemistryAtom Economy CalculatorAtom economy of a reaction, the fraction lost to by-products, the reaction mass efficiency and the E factor.
- ChemistryGibbs Free Energy CalculatorGibbs free energy change, equilibrium constant and crossover temperature from enthalpy and entropy changes.
- ChemistrySerial Dilution CalculatorFinal concentration after a series of equal dilution steps, with the dilution factor and log reduction.
- ChemistryRydberg Equation CalculatorWavelength, frequency and photon energy of a hydrogen emission line from the two energy levels involved.
- ChemistryMole and Particle ConverterConvert moles, millimoles, micromoles and numbers of atoms or molecules.
- ChemistryVan der Waals Equation CalculatorPressure of a real gas from the Van der Waals equation, compared with the ideal gas value.
- ChemistryBragg's Law CalculatorDiffraction angle from lattice spacing, wavelength and order, plus the 2-theta value read off a diffractometer.
- ChemistryAntoine Equation Vapour Pressure CalculatorVapour pressure of a liquid at a given temperature from its Antoine constants, in mmHg, kPa and bar.
- ChemistryAtomic Energy Unit ConverterConvert hartree, electronvolt, rydberg, kJ/mol, kcal/mol and wavenumbers.
Science
Astronomy, earth science, biology and the environment: distances between stars, earthquake energy, population growth and air quality.
- ScienceEquivalent Exposure CalculatorChange the aperture or the ISO and get the shutter speed that keeps the exposure exactly the same, with the stops shown.
- ScienceEquivalent Focal Length CalculatorCrop factor, equivalent focal length, equivalent aperture and equivalent ISO for any sensor size.
- ScienceDistance Between Coordinates CalculatorGreat-circle distance between two points on Earth in kilometres, miles and nautical miles, with the initial bearing.
- ScienceAstrophotography Exposure CalculatorThe longest exposure before stars trail, by the 500 rule, the 600 rule and the NPF rule, with the trail length in pixels.
- ScienceDew Point CalculatorDew point from temperature and relative humidity, with the vapour pressure and absolute humidity.
- ScienceLight Travel Time CalculatorHow long light takes to cross a distance, in seconds, minutes, light years and astronomical units.
- ScienceHeat Index CalculatorApparent temperature in hot, humid weather, with how much above the real temperature it feels.
- ScienceReverberation Time CalculatorRT60 by Sabine and by Eyring, with the room volume, total absorption, Schroeder frequency and critical distance.
- ScienceDaylight Hours CalculatorLength of daylight at a latitude on a given day of the year, with the solar declination and noon sun height.
- ScienceRoom Modes CalculatorThe lowest standing-wave frequencies of a rectangular room, sorted, with each one marked axial, tangential or oblique.
- ScienceEarthquake Energy CalculatorEnergy released by an earthquake in joules and tonnes of TNT, and how it compares with another magnitude.
- ScienceTelescope Magnification CalculatorMagnification from an eyepiece, with the exit pupil, true field of view, useful maximum and limiting magnitude.
- ScienceAltitude Pressure CalculatorAir pressure, temperature, boiling point and oxygen partial pressure at altitude.
- ScienceDistance to the Horizon CalculatorHow far the horizon is from any height, with and without atmospheric refraction, and how far away a tall object stays visible.
- ScienceFlight Carbon Footprint CalculatorGreenhouse gas emissions of a flight per passenger, with and without the high-altitude multiplier.
- ScienceLight Meter CalculatorTurn a meter reading in cd/m² or lux into a shutter speed, for incident or reflected metering, using the ISO 2720 constants.
- ScienceMacro Magnification and Bellows CalculatorMagnification, bellows exposure factor, effective aperture and working distance from the focal length and the extension.
- SciencePopulation Growth CalculatorPopulation after a number of years at a continuous growth rate, with the doubling time.
- ScienceBacterial Growth CalculatorCell count after a period of exponential growth, the number of generations and the time to reach a million per millilitre.
- ScienceCrosswind Component CalculatorCrosswind and headwind components for a wind at an angle to the runway, with the margin to a stated limit.
- ScienceDiffraction Limit CalculatorAiry disk diameter, the f-number where diffraction reaches the pixel pitch, and whether it is visible yet.
- ScienceKepler's Third Law CalculatorOrbital period and speed of a body from its orbital radius and the mass it orbits.
- ScienceCircle of Confusion CalculatorThe circle of confusion for a sensor, by the diagonal rule or from the print size and how sharp you want the print to look.
- ScienceRocket Equation Calculator (Delta-v)Delta-v from specific impulse and the wet and dry masses of a stage, with mass ratio and propellant load.
- ScienceStar Luminosity CalculatorLuminosity of a star in solar units and watts, its peak colour, absolute magnitude and the flux reaching us.
- ScienceStar Magnitude CalculatorBrightness ratio between two magnitudes, and the absolute magnitude of a star at a given distance.
- ScienceEarthquake Epicentre Distance CalculatorDistance to an earthquake from the delay between the P and S waves on a seismogram.
- ScienceReciprocity Failure CalculatorThe corrected exposure time for film at long exposures, by the Schwarzschild law, including any filter stops.
- ScienceSchwarzschild Radius CalculatorThe event horizon radius for a given mass, in metres and kilometres, with the mean density inside it.
- ScienceHohmann Transfer CalculatorThe two burns, total delta-v and travel time to move between two circular orbits.
- ScienceHardy-Weinberg Carrier Frequency CalculatorAllele frequencies, carrier frequency and genotype proportions from the frequency of the recessive phenotype.
- ScienceMichaelis-Menten Enzyme Kinetics CalculatorReaction rate, fraction of Vmax and catalytic efficiency from Vmax, Km and substrate concentration.
- ScienceAstronomical Distance ConverterConvert astronomical units, light-years, parsecs, kilometres and solar radii.
- ScienceRadiation Dose Converter (Sievert and Rem)Convert sievert, millisievert, microsievert, rem and millirem.
- ScienceRadioactivity ConverterConvert becquerel, curie, disintegrations per minute and rutherford.
- ScienceAbsorbed Dose Converter (Gray and Rad)Convert gray, milligray, kilogray, rad and erg per gram.
Time & Dates
Date differences, age, working days, time arithmetic, deadlines and duration conversions.
- Time & DatesAge CalculatorExact age in years, months and days, plus the days, hours and minutes lived and when the next birthday falls.
- Time & DatesDays Between Dates CalculatorExact number of days, weeks, months and hours between two dates.
- Time & DatesHours Between Two TimesWorked hours from a start time, an end time and a break, in decimal and in hours and minutes.
- Time & DatesStopwatchA stopwatch with lap times, showing the elapsed time in seconds, minutes and hours at once.
- Time & DatesWorking Days CalculatorNumber of weekdays between two dates, both dates included.
- Time & DatesCountdown TimerCounts down to a moment, in days, hours, minutes and seconds, and keeps counting past it.
- Time & DatesPregnancy Due Date CalculatorThe estimated due date from the first day of the last menstrual period, by Naegele's rule.
- Time & DatesAdd or Subtract Days from a DateThe date a given number of days before or after a start date.
- Time & DatesWorld ClockFour clocks side by side, each on its own UTC offset, ticking together with UTC itself.
- Time & DatesFlight Arrival Time CalculatorWhat time you land in local time, and whether it is still the same day, from the departure time, the two time zones and the flight length.
- Time & DatesHours and Minutes to DecimalConvert a duration in hours, minutes and seconds into decimal hours.
- Time & DatesTime Zone Difference CalculatorThe local time somewhere else from a time here and the two UTC offsets, with the day shift.
- Time & DatesAdd Hours and MinutesSum of two durations in hours and minutes, in decimal hours, and the difference between them.
- Time & DatesAdd Working Days CalculatorThe date a given number of working days from a start date, skipping weekends.
- Time & DatesWeek Number and Date InfoISO week number, weekday, day of the year and quarter for any date.
- Time & DatesFlight Duration CalculatorThe real time in the air between two local clock times in two different time zones, with the day change accounted for.
- Time & DatesCalendar GeneratorAny month laid out as a grid, starting on Monday or on Sunday, with the working days and weekend days counted.
- Time & DatesWeek Number to DatesWhich Monday to Sunday a given ISO week number covers, and how many weeks that year holds.
- Time & DatesInternational Meeting Time PlannerFind the hours that suit two or three time zones at once, using the UTC offsets you enter.
- Time & DatesJulian Day ConverterTurn a calendar date into a Julian day number, Julian date or Modified Julian date, and back again.
Work & Productivity
Text counting, case conversion, timesheets, hourly rates, random data and small office utilities.
- Work & ProductivityWord and Character CounterCount words, characters, sentences, paragraphs and reading time as you type.
- Work & ProductivityPassword GeneratorGenerates random passwords from the character sets you choose, with the entropy in bits.
- Work & ProductivityHourly Pay CalculatorGross pay from hours worked, hourly rate and overtime at a premium.
- Work & ProductivitySalary ConverterTurn an annual salary into monthly, weekly, daily and hourly figures.
- Work & ProductivityColour PickerPick a colour and get it back as five tints and shades, ready to paste into a stylesheet.
- Work & ProductivityLorem Ipsum GeneratorPlaceholder paragraphs of any length, with the classic opening if you want it.
- Work & ProductivityColour Palette GeneratorBuilds a five-colour palette from one base colour using the classic harmony schemes.
- Work & ProductivityText Case ConverterSwitch text between upper, lower, title, sentence, snake and kebab case.
- Work & ProductivityUUID GeneratorVersion 4 UUIDs in the standard 8-4-4-4-12 form, ready to paste.
- Work & ProductivityAspect Ratio CalculatorResize an image or video while keeping its proportions, with the simplified ratio.
- Work & ProductivityColour ConverterHex, RGB and HSL for a colour, with its complementary and the contrast against black and white.
- Work & ProductivityColour Contrast CheckerThe WCAG contrast ratio between two colours, and whether it passes AA or AAA at the text size you are using.
- Work & ProductivityGrade Needed CalculatorThe mark you need on the final assessment to reach a target average.
- Work & ProductivityInvoice Line Total CalculatorLine total with quantity, unit price, a discount and VAT, showing each step.
- Work & ProductivityText Difference CheckerPut two versions of a text side by side and see exactly which lines were added, removed or left alone.
- Work & ProductivityUsername GeneratorReadable usernames made from two word lists, with or without a trailing number.
- Work & ProductivityFind and ReplaceSwap one piece of text for another everywhere it appears, with control over capitals and whole words.
- Work & ProductivityFreelance Rate CalculatorThe hourly and day rate you need to charge to reach a target income.
- Work & ProductivityTime Card CalculatorHours worked between two clock times, less the break, with the pay and the weekly total.
- Work & ProductivityDecision Matrix CalculatorScore several options against several criteria, weight the criteria by how much each one matters, and get a ranking instead of an argument.
- Work & ProductivityDaily Target CalculatorHow much you have to do each day to finish on time, how long your current pace would actually take, and how far the two are apart.
- Work & ProductivityExtract from TextPull every email address, link, number, hashtag or mention out of a block of text, with the duplicates removed.
- Work & ProductivityPIN GeneratorRandom numeric PINs of any length, with how many combinations exist and the entropy.
- Work & ProductivityEisenhower Matrix GeneratorSort a list of tasks into do now, give it a date, hand it over and let it go, from an urgency mark and an importance mark.
- Work & ProductivityTrue Cost of an EmployeeYearly and monthly cost of a salary once employer contributions and extras are included.
- Work & ProductivityReadability CalculatorThe Flesch Reading Ease score and the school grade it corresponds to, with the sentence and syllable measurements behind them.
- Work & ProductivityText CleanerTidies pasted text in one go: extra spaces, ragged ends and blank lines all removed.
- Work & ProductivityTest Score CalculatorExam percentage from correct answers, the mark on any scale, and how many answers a pass needs.
- Work & ProductivitySales Commission CalculatorCommission above a sales threshold, total pay with the base, and the effective rate on all sales.
- Work & ProductivityOvertime Pay CalculatorTotal pay across normal hours and two overtime bands, with the effective average rate.
- Work & ProductivityText Similarity CheckerHow alike two texts are, letter by letter and by the words they share, with the exact number of edits between them.
- Work & ProductivityTime Allocation CalculatorDivide the hours you actually have between the things you want to do, in proportion to how much each one matters.
- Work & ProductivityWord Frequency CounterHow many times each word appears in a text, from the most common down, with its share of the whole.
- Work & ProductivityHoliday Entitlement CalculatorHow many days off you have earned so far this year, how many you have left, and what a full year would give you.
- Work & ProductivityRemove Empty LinesTake the blank lines out of a block of text and leave everything else exactly as it was.
- Work & ProductivitySort Text LinesPuts a list of lines in alphabetical order, reverse order, or from shortest to longest.
- Work & ProductivityTyping Speed CalculatorGross and net words per minute from a timed passage, with accuracy and characters per minute.
- Work & ProductivityMeeting Cost CalculatorWhat a meeting costs in salary terms, per occurrence and per year.
- Work & ProductivityRemove Duplicate LinesStrips repeated lines from a list and tells you how many went.
- Work & ProductivityPassword Entropy CalculatorEntropy in bits for a random password of a given length and alphabet, with a brute-force time estimate.
- Work & ProductivitySubnet Mask CalculatorUsable hosts, total addresses and the four octets of the subnet mask for a CIDR prefix.
- Work & ProductivityRemove Duplicate WordsKeep the first appearance of every word and throw the repeats away, ignoring capitals and punctuation.
- Work & ProductivityRemove Extra SpacesCollapses runs of spaces and tabs to one and trims the ends of every line.
- Work & ProductivityFile Transfer Time CalculatorTime to send or receive a file over a connection, allowing for real-world overhead.
- Work & ProductivityVideo File Size CalculatorFile size of a video from its bitrate and length, the recording time on a card, and the bitrate that would fill it exactly.
- Work & ProductivityConversion Rate and ROAS CalculatorConversion rate, revenue, cost per conversion and return on ad spend from one set of numbers.
- Work & ProductivityRemove Line BreaksJoins a text broken across many lines back into one flowing paragraph.
- Work & ProductivityBurn Rate and Runway CalculatorMonths of cash remaining, the net monthly burn and how much of costs revenue already covers.
- Work & ProductivityPomodoro PlannerHow many focus blocks a task needs, the real time it takes with breaks, and the share of that time spent working.
- Work & ProductivityRender Time CalculatorHow long a render will take on a given number of machines, with the total frames, the cost and the real speedup.
- Work & ProductivityBillable Utilisation Rate CalculatorShare of hours that are billable, and the effective rate once unbillable time is included.
- Work & ProductivityPERT Three-Point Estimate CalculatorExpected duration from optimistic, likely and pessimistic estimates, with confidence ranges.
- Work & ProductivityPaper Weight (GSM) CalculatorWeight of a sheet and of a whole ream, from the sheet size and grammage.
- Work & ProductivityReverse TextWrites a text backwards, character by character.
- Work & ProductivityRoll Length CalculatorLength of material on a roll from its outside and core diameters, with the number of turns, area and weight.
- Work & ProductivityFree Space Path Loss CalculatorPath loss and received signal level for a radio link, from distance, frequency, power and antenna gains.
- Work & ProductivityReorder Point and Safety Stock CalculatorThe stock level at which to order again, and how much buffer to hold against a bad week.
- Work & ProductivityShannon Channel Capacity CalculatorThe theoretical maximum error-free data rate of a channel from its bandwidth and signal-to-noise ratio.
- Work & ProductivityFresnel Zone CalculatorRadius of the first Fresnel zone at any point along a radio path, and the 60% clearance normally required.
Developers
JSON, CSV, XML, Base64, URL and HTML tools, minifiers, regular expressions and timestamps. Everything runs in your browser.
- DevelopersQR Code GeneratorMakes a QR code from any text or link, entirely in your browser.
- DevelopersJSON FormatterIndents, sorts or minifies JSON, keeping every number exactly as you wrote it.
- DevelopersUnix Timestamp ConverterConverts between Unix time and a readable UTC date, in both directions.
- DevelopersBase64 EncoderEncodes text to Base64, handling accents and any other UTF-8 correctly.
- DevelopersRegex TesterRuns a regular expression against text and shows every match and capture group.
- DevelopersBase64 DecoderDecodes Base64 back to text, with or without padding, plain or URL-safe.
- DevelopersJSON ValidatorSays whether a JSON document is valid and, if not, exactly where it breaks.
- DevelopersURL EncoderPercent-encodes text so it can be dropped safely into a URL or a query string.
- DevelopersJSON to CSV ConverterTurns a JSON array of objects into a comma-separated table you can open in a spreadsheet.
- DevelopersURL DecoderTurns a percent-encoded link back into readable text, UTF-8 included.
- DevelopersCSV to JSON ConverterTurns a CSV table into a JSON array of objects, guessing numbers and booleans.
- DevelopersMarkdown to HTML ConverterTurns Markdown into clean HTML, with everything escaped safely first.
- DevelopersCSS MinifierStrips comments and needless whitespace from a stylesheet, safely.
- DevelopersQR Code CustomizerThe same QR code with your own colours, module size and quiet zone, as a downloadable SVG.
- DevelopersHTML EncoderEscapes the five characters that would otherwise be read as markup.
- DevelopersBarcode GeneratorCode 128 and EAN-13 barcodes as SVG, with the check digit worked out for you.
- DevelopersURL ParserBreaks a link into scheme, host, port, path, query parameters and fragment.
- DevelopersHTML DecoderTurns HTML entities back into the characters they stand for.
- DevelopersImage ResizerChange the pixel size of a picture without leaving the page — fit it in a box, cover one, or scale it by a percentage.
- DevelopersXML FormatterIndents XML so the structure is visible, or strips the whitespace back out again.
- DevelopersHTML MinifierCollapses whitespace and removes comments, leaving pre and script blocks alone.
- DevelopersImage CompressorSqueeze a photo down to a smaller file at the same pixel size, and see exactly how many bytes you saved.
- DevelopersJavaScript MinifierRemoves comments and spare whitespace from JavaScript, conservatively.
- DevelopersHash GeneratorThe SHA-256, SHA-512, SHA-1 or MD5 hash of any text, in hex, capitals and Base64, worked out in your browser.
- DevelopersXML ValidatorChecks that an XML document is well formed and says which tag broke it.
- DevelopersImage ConverterTurn a picture into PNG, JPEG or WebP in your browser, and see what the change does to the file size.
- DevelopersImage to PDF ConverterPut a picture on an A4 or Letter page and save it as a PDF, with the margin and orientation you choose.
- DevelopersCSS Gradient GeneratorBuild a linear, radial or conic gradient and get the CSS line, with the contrast between the two ends.
- DevelopersImage CropperKeep a rectangle of a picture and throw the rest away, with the exact pixel numbers rather than a rough drag.
- DevelopersPassphrase GeneratorA password made of random common words, with the exact entropy stated so you can judge it rather than trust it.
- DevelopersBox Shadow GeneratorBuild a CSS box shadow or text shadow from the offsets, blur, spread and colour, and see how much room it needs.
- DevelopersPNG to JPG ConverterSave a PNG as a JPEG at the quality you choose, and see how many bytes that costs or saves.
- DevelopersRandom Token GeneratorRandom strings in hex, Base58, Base64 or digits, with the exact number of bits of entropy they carry.
- DevelopersVideo Bitrate CalculatorBitrate from resolution, frame rate and bits per pixel, with the file size, the raw uncompressed rate and the compression ratio.
- DevelopersScreen Resolution CheckerThe size of the screen you are on, in the pixels pages are told about and in the pixels the panel really has.
- DevelopersBorder Radius GeneratorSet four corners and get the shortest CSS that produces them, with a warning when the box is too small to hold them.
- DevelopersJPG to PNG ConverterSave a JPEG photograph as a PNG file, in your browser, without sending it anywhere.
- DevelopersHTML PreviewPaste HTML and see it drawn straight away, with a count of the elements and a list of any tags left open.
- DevelopersAudio File Size CalculatorHow much space uncompressed audio takes, from the sample rate, bit depth, channels and length — and how much a compressed version would take.
- DevelopersBrowser CheckerWhat browser you are using, which version, which engine and which system — read from the line your browser announces.
- DevelopersStreaming Bandwidth CalculatorPeak bandwidth for a number of concurrent viewers, and the monthly data transfer and cost that follow from it.
- DevelopersWebP to JPG ConverterTurn a WebP picture into an ordinary JPEG that any program will open.
- DevelopersDevice CheckerWhat your browser is willing to say about the machine underneath: platform, processor cores, memory and touch.
- DevelopersAudio Latency CalculatorBuffer latency in milliseconds, round-trip delay, and the distance you would have to stand back to feel the same thing.
- DevelopersColour Depth CalculatorLevels per channel, total colours, raw bitrate and the size of one banding step, for any bit depth.
- DevelopersFFT Resolution CalculatorFrequency bin width, window length, usable bins and hop size, from the sample rate and the FFT size.
- DevelopersChroma Subsampling CalculatorData rate and frame size for 4:4:4, 4:2:2, 4:2:0 and 4:1:1, with the chroma resolution and what each one saves.
- DevelopersGOP and Keyframe Interval CalculatorGOP duration in seconds, keyframes per minute, the I, P and B counts inside a GOP, and whether it lines up with the segment length.
Everyday
Tips, discounts, splitting bills, cooking measures, travel and the small calculations that come up every week.
- EverydayTip CalculatorTip amount, total bill and the share per person, all at once.
- EverydayRandom PickerPicks one or several entries at random from a list you paste in, with a seed you can publish.
- EverydayUnit Price ComparisonCompare two package sizes by price per 1000 units of quantity.
- EverydayFeet and Inches to CentimetresConvert a height in feet and inches to centimetres, or back again.
- EverydayCooking Measurement ConverterConvert cooking volumes into grams and ounces for common ingredients.
- EverydayCoin FlipFlips one coin or a thousand, with the count of heads and tails and the longest run.
- EverydayDice RollerRolls any number of dice with any number of sides, with a modifier, total, highest and lowest.
- EverydayLottery Number GeneratorDraws a line of lottery numbers for any format, and shows how many combinations exist.
- EverydayRandom WheelSpins a list and gives you a winner, a runner-up and the full running order.
- EverydaySplit the Bill CalculatorEqual share per person, with a rounded-up amount and the small surplus it creates.
- EverydayShoe Size ConverterEuropean, UK, US and Mondopoint shoe sizes from the length of the foot in centimetres.
- EverydayTeam GeneratorSplits a list of names into balanced teams at random, with the seed recorded.
- EverydayOven Temperature ConverterCelsius, Fahrenheit, gas mark and the fan-oven equivalent, all at once.
- EverydayRecipe ScalerRescale any ingredient quantity from one number of servings to another.
- EverydayEgg Boiling Time CalculatorHow long to boil an egg for a chosen yolk temperature, from its weight and starting temperature.
- EverydayPros and Cons CalculatorA for-and-against list where each reason carries the weight you give it, so the answer reflects what matters and not just how many things you thought of.
- EverydayHeat Pump Running Cost CalculatorAnnual heating cost of a heat pump against a gas boiler, with the SCOP needed to break even.
- EverydayWeighted Decision MakerLet chance choose between your options, but give the ones you lean towards a better chance of coming up.
- EverydayDefrosting Time CalculatorHow long frozen food takes to thaw in the fridge or in cold water, with the number of water changes needed.
- EverydayAir Conditioner Size CalculatorAdd up the heat a room gains and turn it into watts and BTU per hour, so you can match a unit to the room rather than guess.
- EverydayReading Time CalculatorHow long a text takes to read silently, to read aloud, and how many pages it fills.
- EverydayBingo Card GeneratorA standard 75-ball bingo card, five by five, with the free centre square.
- EverydayHousehold Water Usage CalculatorAdd up what your home actually uses — showers, flushes, washing, everything else — in litres a day and money a month.
- EverydayAir Fryer Conversion CalculatorAir fryer temperature and time from an oven recipe, with the point to shake or turn the food.
- EverydayCoffee to Water Ratio CalculatorGrams of coffee for a volume of water, and how much brewed coffee you actually end up with.
- EverydayScreen Size CalculatorActual width and height of a screen from its diagonal and aspect ratio.
- EverydayRandom Card GeneratorDraws cards from a shuffled 52-card deck, without ever repeating one.
- EverydayDog Age CalculatorA dog's age in human-equivalent years by the epigenetic formula, with the old seven-year rule for comparison.
- EverydayRaised Bed Soil CalculatorLitres of soil or compost needed to fill a raised bed or planter, with the number of bags and the cost.
- EverydayTV Viewing Distance CalculatorIdeal seating distance for a screen size, based on the horizontal angle it fills.
- EverydayAlcohol Units CalculatorGrams of pure alcohol in a drink, in UK units, US standard drinks and calories.
- EverydayBread Hydration CalculatorWater, salt and starter weights for a given flour weight, using baker's percentages.
- EverydayBaggage Allowance CalculatorHow far over the weight limit your case is, what the excess will cost across all your bags, and whether it is within the size rule.
- EverydayPizza Value CalculatorWhich pizza gives more area for the money, and by how much.
- EverydayRoast Cooking Time CalculatorOven time for a joint from its weight, plus resting time and the finish time in hours and minutes.
- EverydayShower Cost CalculatorCost and energy of one shower, the water used, and the yearly cost for a household.
- EverydaySubscription Cost CalculatorYearly and monthly total of your subscriptions, what share of income they take and what five years costs.
- EverydayDilution Ratio CalculatorConcentrate and water needed for a final volume at a given dilution ratio.
- EverydayRandom Emoji GeneratorDraws random emoji from a chosen category, or from all of them at once.
- EverydayParty Food Quantity CalculatorHow much main course, sides and bread to buy for a number of guests, with a margin.
- EverydayPhone Charging Time CalculatorTime to charge a phone from its current level, with the battery's energy in watt-hours.
- EverydayPlant Spacing CalculatorHow many plants fit a plot at a given spacing, in rows and in total, with the density per square metre.
- EverydayBaking Pan Conversion CalculatorFactor to scale a recipe when your tin is a different size or shape from the one in the book.
- EverydayWill This Bed Fit CalculatorHow much floor is left on each side and at the foot once a given bed is in a given room, and the widest bed the room takes.
- EverydayParty Drinks CalculatorDrinks, wine bottles, soft drinks, ice and glasses for a party of a given size and length.
- EverydayWashing Machine Cost CalculatorCost of one wash cycle and of a year of washing, with the electricity and water it uses.
- EverydayMobile Data Usage CalculatorMonthly data use from video, music and browsing hours, with the share video takes.
- EverydayPool Chlorine Dose CalculatorProduct needed to raise pool chlorine to a target level, in grams and kilograms, with the pure chlorine equivalent.
- EverydayPet Food Portion CalculatorDaily and per-meal food quantity for a dog or cat, from its weight and activity level.
- EverydayPhoto Print Size and DPI CalculatorPrint size at a chosen resolution, and the resolution you would get at 30 cm wide.
- EverydayDepth of Field CalculatorNear and far limits of sharpness, the total depth of field and the hyperfocal distance.
- EverydayRing Size CalculatorInner diameter of a ring from the finger circumference, in millimetres, centimetres and inches.
- EverydayWater Tank Fill Time CalculatorTime to fill a tank from its current level at a given flow rate.
- EverydayWind Chill CalculatorHow cold the air feels on exposed skin once the wind is taken into account.
- EverydayPicture Hanging CalculatorEven spacing for a row of pictures and the nail height for eye-level hanging.
- EverydaySourdough Starter Feeding CalculatorFlour and water to feed a starter at a chosen ratio, how much you end up with, and how much to keep back.
- EverydayStandby Power Cost CalculatorYearly cost and energy of devices left on standby, per device and in total, with the carbon behind it.
- EverydayAquarium Water Change CalculatorUsable litres in a tank and the volume of a partial water change, with the dose of conditioner needed.
- EverydayGarden Watering CalculatorLitres a garden needs each week, how long to run the hose, and what it costs over a year.
- EverydayMoving Boxes CalculatorRough number of packing boxes for a house move, split by box size.
- EverydayMusical Note Frequency CalculatorFrequency of a note a number of semitones from A4, with its MIDI number, wavelength and the octave above.
- EverydayBicycle Gear CalculatorDevelopment, gear ratio, gear inches and road speed for a chainring and sprocket combination.
- EverydayBrine Salt CalculatorSalt needed for a brine at a chosen strength, in grams and tablespoons, with the strength counting the food as well.
- EverydayExposure Value CalculatorExposure value from aperture, shutter and ISO, with the EV at ISO 100 and the light level it corresponds to.
- EverydayFirewood Stack Volume CalculatorStacked volume of a woodpile and the solid wood it actually contains.
- EverydayField of View CalculatorHorizontal, vertical and diagonal angles of view, the frame size at a distance, and the crop factor.
- EverydayGrass Seed CalculatorSeed needed for a new lawn, bags and cost, with the lighter rate for overseeding an existing one.
- EverydayPrinting Cost Per Page CalculatorCost of a printed page including paper, with the monthly and yearly total and when the cartridge runs out.
- EverydayLawn Fertiliser CalculatorHow much product to spread for a target nitrogen dose, the rate per square metre, bags needed and cost.
- EverydayTempo to Delay Time CalculatorDelay times in milliseconds for a tempo, from quarter notes down to sixteenths, with dotted and triplet values.
- EverydayCurtain Fabric CalculatorHow much fabric a pair of curtains needs, counted in whole fabric widths.
- EverydayCompost C:N Ratio CalculatorThe carbon to nitrogen ratio of a compost mix from the weights and analyses of two materials.
- EverydayFrame Rate and Frame Count CalculatorFrames in a clip, how long one frame lasts, and what happens when you change the rate.
Automotive
Fuel consumption, trip cost, speed and distance, engine figures and tyre or wheel calculations.
- AutomotiveFuel Consumption CalculatorReal consumption from a tankful, in L/100 km, km/L and both kinds of mpg.
- AutomotiveTrip Cost CalculatorWhat a journey really costs: fuel, tolls and parking, with the total split per person and per kilometre.
- AutomotiveEV Charging Cost CalculatorCost of a charge, energy drawn from the socket, range added and cost per kilometre.
- AutomotiveFuel Cost Comparison CalculatorCompare two cars on what they cost per 100 km, whatever they run on, and see how far you drive before a higher purchase price pays for itself.
- AutomotiveTyre Size CalculatorOverall diameter, rolling circumference and sidewall height from a tyre code.
- AutomotiveEV Range CalculatorHow far an electric car actually goes once you take off the unusable part of the battery, the reserve you keep and the cold or the motorway.
- AutomotiveBraking Distance CalculatorStopping distance split into reaction distance and braking distance, plus the total time.
- AutomotiveFuel Savings CalculatorYearly fuel and money saved by switching to a car with lower consumption.
- AutomotiveCar Lease CalculatorWork a lease payment out from the price, the residual value and the rate, and see how much of it is the car losing value and how much is interest.
- AutomotiveAnnual Car Cost CalculatorTotal yearly cost of running a car, per month and per kilometre.
- AutomotiveCarpool Cost CalculatorFair share per passenger for fuel and tolls on a shared journey.
- AutomotiveMileage Allowance CalculatorYearly mileage reimbursement, what the fuel alone costs, and the margin between the two.
- AutomotivePower-to-Weight Ratio CalculatorPower per tonne and kilograms per horsepower, including passengers and luggage.
- AutomotiveEngine Displacement CalculatorEngine capacity in cubic centimetres and litres from bore, stroke and cylinder count.
- AutomotiveGear Speed CalculatorRoad speed at a given engine speed in a chosen gear, plus the wheel speed and overall ratio.
- AutomotiveCompression Ratio CalculatorStatic compression ratio from bore, stroke and combustion chamber volume, with the swept volume.
- AutomotiveSpeedometer Error from Tyre SizeHow much a change of tyre size shifts the indicated speed and the odometer reading.
- AutomotiveTyre Pressure Temperature CalculatorHow tyre pressure changes with temperature, in bar, psi and as a percentage.
- AutomotiveTrailer Tongue Weight CalculatorDownload on the towball for a loaded trailer, against the limit of your towbar.
- AutomotiveWheel Offset and Backspacing CalculatorBackspacing from wheel width and ET offset, and the change when swapping to a different offset.
- AutomotiveRegenerative Braking Energy CalculatorWork out how much energy braking releases and how much of it a car can put back in the battery.
Health & Fitness
Informational body and activity calculators. They never replace a qualified health professional.
- Health & FitnessBMI CalculatorBody mass index, its standard category and the weight range for a BMI of 18.5 to 24.9.
- Health & FitnessBMR and Daily Calorie CalculatorBasal metabolic rate by the Mifflin-St Jeor equation, and daily needs at your activity level.
- Health & FitnessRunning Pace CalculatorPace per kilometre and per mile from a distance and a finishing time, with average speed.
- Health & FitnessWater Intake Reference CalculatorA rough daily water reference from body weight and exercise time.
- Health & FitnessCalories Burned CalculatorEnergy used during an activity from its MET intensity, your weight and the duration.
- Health & FitnessHeart Rate Zones CalculatorEstimated maximum heart rate and the 60, 70, 80 and 90 percent training thresholds.
- Health & FitnessBody Fat Calculator (US Navy Method)Estimated body fat percentage, fat mass and lean mass from neck, waist, hip and height measurements.
- Health & FitnessSleep Cycle CalculatorTime in bed needed for a number of sleep cycles, including the time it takes to fall asleep.
- Health & FitnessCalorie Deficit CalculatorTime to reach a target weight at a chosen daily calorie deficit, and the intake it implies.
- Health & FitnessIdeal Body Weight CalculatorDevine and Robinson ideal weights for both sexes, alongside the healthy BMI weight range.
- Health & FitnessRace Finish Time CalculatorFinish time for any distance from a target pace per kilometre, with the average speed.
- Health & FitnessSteps to Distance CalculatorDistance walked from a step count, with stride length estimated from your height.
- Health & FitnessMacronutrient CalculatorDaily grams of protein, carbohydrate and fat from a calorie target and a percentage split.
- Health & FitnessOne Rep Max CalculatorEstimated maximum single lift from a set, by two published formulas, with common training percentages.
- Health & FitnessWaist-to-Height Ratio CalculatorWaist measurement divided by height, with the half-height reference value.
- Health & FitnessCycling Power CalculatorThe watts needed to hold a speed, split between air resistance, rolling resistance and the gradient.
- Health & FitnessKarvonen Target Heart Rate CalculatorTraining heart rate zone from the heart rate reserve method, using your resting pulse.
- Health & FitnessWaist to Hip Ratio CalculatorWaist-to-hip ratio, with the waist measurement that would meet the commonly cited thresholds.
- Health & FitnessBody Surface Area CalculatorBody surface area by the Mosteller, Du Bois and Haycock formulas, with the BMI alongside.
- Health & FitnessSwimming Pace CalculatorPace per 100 metres, speed, number of lengths and the average time per length.
- Health & FitnessCooper Test VO₂ Max CalculatorEstimated VO₂ max from the distance covered in a 12-minute run, with the MET equivalent.
- Health & FitnessLean Body Mass Calculator (Boer Formula)Lean mass, fat mass and implied body fat percentage from height, weight and sex.