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Every calculator, one search box.
Type a conversion and the answer appears right here. Or search the whole library — calculators and converters for work, study and everyday life.
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- 1306tools
- 18categories
- 310units
- 4languages
Calculations run in your browser. Your numbers stay on your device.
- 01Percentage CalculatorThe three questions people actually ask about percentages, answered at once, including the reverse ones.Mathematics
- 02Ohm's Law CalculatorEnter any two of voltage, current and resistance and get the third, plus the power.Electricity
- 03Length ConverterConvert between metres, centimetres, inches, feet, yards, miles and nine other length units.Converters
- 04Compound Interest CalculatorFuture value of savings with compound interest and optional monthly contributions.Finance
- 05Electricity Cost CalculatorDaily, monthly and yearly running cost of any appliance from its wattage and hours of use.Electricity
- 06Discount CalculatorFinal price after a percentage discount, and how much you save.Finance
- 07Temperature ConverterConvert between Celsius, Fahrenheit, Kelvin and Rankine, with the offset handled correctly.Converters
- 08Loan Payment CalculatorMonthly instalment, total paid and total interest on a loan repaid in equal payments.Finance
- 09Age CalculatorExact age in years, months and days, plus the days, hours and minutes lived and when the next birthday falls.Time & Dates
- 10BMI CalculatorBody mass index, its standard category and the weight range for a BMI of 18.5 to 24.9.Health & Fitness
- 11QR Code GeneratorMakes a QR code from any text or link, entirely in your browser.Developers
- 12Percentage Change CalculatorFind the percentage increase or decrease between two values, with the absolute difference.Mathematics
Browse by category
Every tool is filed under a category, and every category page lists all of them.
- 100MathematicsPercentages, fractions, powers, geometry, statistics and everyday maths, each one showing the steps behind the result.
- 60StatisticsAverages, spread, correlation and the tests that say whether a difference is real — each one showing the numbers it rests on.
- 26ConvertersMetric, imperial and technical units converted from a single shared library, so every factor is identical across the whole site.
- 106ElectricityOhm's law, single and three-phase power, voltage drop, cable sizing and electronics basics.
- 72MechanicsForce, torque, rotation, gear ratios, belt speed, stress and the mechanical calculations used on the shop floor.
- 46EngineeringIndustrial and process engineering: OEE, takt time, capacity, efficiency, tolerances and unit-heavy technical work.
- 75Construction & DIYConcrete, paint, tiles, flooring, slopes, excavation and material quantities for real building jobs.
- 104FinanceInterest, loans, savings, inflation, margin, markup and VAT. Informational calculators, not financial advice.
- 72PhysicsMotion, forces, energy, momentum, rotation, waves, light and radioactivity — the physics formulas used in school and at work.
- 44Heat & FluidsPressure, 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.
- 49ChemistryConcentrations, dilutions, gas laws, pH and buffers, reaction yields and rates, each one stating the law it comes from.
- 88ScienceAstronomy, earth science, biology and the environment: distances between stars, earthquake energy, population growth and air quality.
- 25Time & DatesDate differences, age, working days, time arithmetic, deadlines and duration conversions.
- 85Work & ProductivityText counting, case conversion, timesheets, hourly rates, random data and small office utilities.
- 90DevelopersJSON, CSV, XML, Base64, URL and HTML tools, minifiers, regular expressions and timestamps. Everything runs in your browser.
- 145EverydayTips, discounts, splitting bills, cooking measures, travel and the small calculations that come up every week.
- 52AutomotiveFuel consumption, trip cost, speed and distance, engine figures and tyre or wheel calculations.
- 67Health & FitnessInformational body and activity calculators. They never replace a qualified health professional.
How it works
Find the tool
Search by name, by unit or by what you want to calculate. Aliases mean "bar to psi" finds the pressure converter.
Type your values
Every field is labelled with its unit. The result updates as you type, in your browser, with nothing sent anywhere.
Understand the result
Each tool shows the formula it used, a worked example and the limits of what it can tell you.
Recently added
The newest additions to the library.
- EngineeringAutomation ROI CalculatorHow many years a robot cell or automatic machine takes to pay back from the labour and other savings it brings, with and without the discount rate, its net present value and its return over its life.
- EngineeringPneumatic Cylinder Sizing CalculatorThe smallest bore that delivers a given force at your pressure, the standard bore to order, its usual rod and the real force out and back.
- EngineeringCompressed Air Pressure Drop CalculatorThe pressure lost along a compressed air pipe for a given flow, length and inner diameter, the air speed inside it and the smallest pipe that keeps the loss within your limit.
- EngineeringCompressed Air Leak Cost CalculatorHow much free air a set of leaks lets out at your network pressure, the compressor power it takes and what that costs in electricity per year.
- EngineeringVacuum Suction Cup CalculatorThe holding force a vacuum gripper needs for a part, the force on each cup, the smallest cup diameter and whether the cups you have in mind hold it.
- EngineeringMachine Hour Rate CalculatorWhat one productive hour of a machine costs, split into depreciation, interest, floor space, maintenance and energy, plus its total cost per year.