106 tools
Electricity
Ohm's law, single and three-phase power, voltage drop, cable sizing and electronics basics.
Tools in this category
- 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.
- ElectricityResistor Color Code Calculator (4 and 5 Bands)Resistance and tolerance range of a resistor from the colours of its bands, for 4-band and 5-band resistors.
- 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.
- Electricity4–20 mA Scaling Calculator (Current Loop to Process Value)The process value a 4–20 mA signal stands for, its position in the span, the current for a given process value, the voltage across a sense resistor and what the NAMUR NE43 limits say about the reading.
- ElectricityPCB Trace Width Calculator (IPC-2221, Current and Temperature Rise)Width of a copper trace for a current and an accepted temperature rise, on an outer or inner layer, with its resistance, voltage drop and power loss.
- ElectricityLM317 Output Voltage Calculator (Resistor Values for the Adjustable Regulator)The output voltage of an LM317 from its two resistors, the R2 needed for the voltage you want, the input voltage it requires and the heat it has to dissipate.
- 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.
- ElectricityADC Resolution, ENOB and Aliasing CalculatorStep size, ideal signal-to-noise ratio, effective number of bits, quantisation noise and the alias frequency of a signal sampled by an analogue-to-digital converter.
- ElectricityButterworth LC Low-Pass Filter Calculator (Coil and Capacitor Values)Capacitor and inductor values of a 2nd to 5th order Butterworth LC low-pass filter between equal source and load resistances, and its attenuation at any frequency.
- ElectricityCapacitor Code Calculator (104, 473, 222…)Capacitance in picofarads, nanofarads and microfarads from the three-digit code printed on ceramic and film capacitors.
- ElectricityCrystal Load Capacitor Calculator (Oscillator Capacitors C1, C2)The two capacitors to fit on a crystal oscillator for the crystal's specified load capacitance, the load you actually get with the parts you have, and the frequency error that difference causes.
- ElectricityI2C Pull-Up Resistor Calculator (SDA and SCL)The window of pull-up resistor values that an I2C bus allows for its supply voltage, speed mode and bus capacitance, and whether the resistor you picked sits inside it.
- ElectricitySallen-Key Low-Pass Filter Calculator (Unity-Gain, Second Order)Cut-off frequency, natural frequency, Q and passband peaking of a unity-gain Sallen-Key low-pass filter from its two resistors and two capacitors, and the C1 that makes it maximally flat.
- ElectricitySolenoid Calculator (Magnetic Field and Inductance)Magnetic field inside a coil, its inductance by the long-coil formula and by Wheeler's formula, stored energy and flux, with the coil drawn to scale.
- Electricity555 Timer Calculator (Astable and Monostable)Frequency, high and low times and duty cycle of a 555 timer in astable mode from R1, R2 and C, and the pulse length in monostable mode.
- ElectricityUART Baud Rate Calculator (Error, Divisor and Transfer Time)The divisor to load for a baud rate, the error it leaves with your clock (in normal and double-speed mode), the bits that make up a frame, the real data rate and the time to send a message.
- ElectricityVSWR and Return Loss Calculator (Antenna and Cable Mismatch)VSWR, reflection coefficient, return loss, mismatch loss and the power reflected back, from the line impedance and the load you actually have.
- ElectricityJunction Temperature and Heatsink CalculatorTemperature of a semiconductor's junction, case and heatsink from the power it dissipates and the chain of thermal resistances, plus the largest heatsink resistance you can get away with.
- 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.
- ElectricityCurrent Divider CalculatorHow a current splits between two or three resistors in parallel, with the equivalent resistance and the voltage across them.
- ElectricityMicrostrip Impedance Calculator (PCB Trace)Characteristic impedance and propagation delay of a PCB trace over a ground plane, by the IPC-2141 formula, with a check of its range of validity.
- ElectricityBrushless Motor Kv and Torque Constant Calculator (BLDC, Drone Motors)The torque constant, no-load speed, speed and torque under load, shaft power and efficiency of a brushless motor from its Kv rating, voltage, current, no-load current and winding resistance.
- ElectricityBoost Converter Calculator (Duty Cycle and Inductor)Duty cycle, inductor value, ripple and peak current, and input current of a step-up (boost) converter from the voltages, load current, switching frequency and efficiency.
- ElectricityBuck Converter Calculator (Duty Cycle and Inductor)Duty cycle, inductor value, ripple and peak current, and input current of a step-down (buck) converter from the voltages, load current, switching frequency and efficiency.
- ElectricityCoaxial Cable Impedance CalculatorCharacteristic impedance, capacitance and inductance per metre, velocity factor and delay of a coaxial line, with its cross-section drawn to scale.
- ElectricitydBm to Watts ConverterConvert a power in dBm to milliwatts, watts and dBW, with the RMS voltage it produces across a 50 Ω load.
- ElectricityEIRP, ERP and Field Strength Calculator (Antenna Power and Exposure Distance)Effective radiated power from the transmitter power, cable loss and antenna gain, the field strength and power density at a distance, and how far away a power-density limit is met.
- ElectricityL-Network Impedance Matching Calculator (Antenna Tuner, RF Match)Coil and capacitor values of an L-network that matches one resistance to another at a chosen frequency, in both the low-pass and the high-pass version.
- ElectricityMotor Synchronous Speed and Slip CalculatorSynchronous speed of an AC motor from the supply frequency and number of poles, and the slip of an induction motor from its nameplate speed.
- ElectricityNoise Figure Cascade Calculator (Friis Formula)Total noise figure, noise temperature and gain of a receive chain of up to three stages (low-noise amplifier, cable, mixer, amplifier), and how much of the noise comes from the stages after the first.
- ElectricityPi and T Attenuator Calculator (Resistive Pad Values)The resistor values of a matched T or pi attenuator for a given attenuation and impedance, and the power the pad has to dissipate.
- ElectricityPower Supply Hold-Up Capacitor Calculator (Bulk Capacitor Sizing)The bulk capacitance a power supply needs to ride through a given hold-up time, the energy that involves, and the hold-up time a capacitor you already have would give.
- ElectricityOscilloscope Bandwidth and Rise Time CalculatorThe rise time an oscilloscope and probe will show for a given signal, the error that adds, the bandwidth the signal really contains and the system bandwidth needed to measure it within a chosen error.
- ElectricitySkin Depth Calculator (Skin Effect)How deep alternating current really flows in a conductor at a given frequency, the largest strand worth using, and an estimate of the extra AC resistance.
- ElectricityStrain Gauge Bridge Calculator (Wheatstone Output, Quarter, Half, Full)The output of a strain gauge Wheatstone bridge for a given strain, gauge factor and excitation, for quarter, half and full bridges, with the resistance change and the non-linearity of the quarter bridge.
- ElectricityThermal Noise and Receiver Sensitivity Calculator (kTB)The thermal noise floor of a receiver for its bandwidth and temperature, the weakest signal it can decode from its noise figure and the SNR it needs, and the noise voltage across a resistor.
- ElectricityTotal Harmonic Distortion (THD) Calculator for Voltage and CurrentTHD from the fundamental and up to six harmonics, the same distortion against the total RMS value (THD-R), the total RMS and the largest single harmonic.
- ElectricityThree-Phase Voltage Unbalance Calculator (NEMA and IEC)Percentage voltage unbalance of a three-phase supply from the three line voltages, by the NEMA definition and by the IEC negative-sequence definition, with what it means for a motor.
- ElectricityUPS and Battery Backup Runtime CalculatorWork out how long a battery bank will carry a given load through a power cut.
- ElectricityAC Generator EMF Calculator (Faraday's Law)Peak, RMS and instantaneous voltage of a coil spinning in a magnetic field, with the sine wave drawn over two turns.
- ElectricityCapacitor Discharge Time CalculatorHow long a capacitor takes to discharge through a resistor to a safe voltage, the voltage left after any time, and the energy it held.
- ElectricityConduit Fill Calculator (Cables in a Conduit or Trunking)How full a conduit is with a given number of same-size cables, the fill the code allows for that number of cables, and the most cables that fit.
- ElectricityDish Antenna Gain Calculator (Parabolic Reflector, dBi)Gain in dBi, beamwidth and effective aperture of a parabolic dish from its diameter, the frequency and the aperture efficiency.
- ElectricityGround Rod Resistance Calculator (Earth Electrode, Dwight)Resistance to earth of a single vertical ground rod from the soil resistivity, rod length and diameter, and the voltage it rises to for a given current.
- ElectricityMaximum Power Transfer Calculator (Load Matching)Power, voltage, current and efficiency in a load fed from a source with internal resistance, and how close that load comes to the most the source could ever deliver.
- ElectricityNichrome Wire Calculator (Heating Element Length)Length of nichrome wire for a heating element of a given voltage and power, with the resistance, the current and the power per area of wire surface.
- ElectricityNTC Thermistor Calculator (Beta Equation)Temperature from the resistance of an NTC thermistor, and its resistance at any temperature, using the B (beta) value from the datasheet.
- ElectricityOp-Amp Slew Rate and Full-Power Bandwidth CalculatorThe highest frequency an op-amp can reproduce at a given output amplitude, the slew rate your signal needs, and the largest undistorted swing at your frequency.
- ElectricityParallel Plate Capacitor Calculator (Capacitance from Area, Gap and Dielectric)Capacitance, charge, stored energy and electric field of two parallel plates from their area, the gap, the insulator between them and the voltage.
- ElectricityRC Filter Frequency Response CalculatorGain in dB, output-to-input ratio and phase shift of a first-order RC low-pass or high-pass filter at any frequency, with its response curve drawn.
- ElectricityRectifier Ripple Calculator (Smoothing Capacitor)Peak-to-peak ripple voltage on the smoothing capacitor of a half-wave or full-wave rectifier, and the capacitance needed for a ripple you can accept.
- ElectricityRL Circuit Calculator (Inductor Current and Time Constant)Current in a coil a given time after a voltage is switched on, the final current, the time constant L ÷ R and the energy stored in the magnetic field.
- ElectricitySolar Panel Temperature Calculator (NOCT and Power Loss)Cell temperature of a solar panel from the air temperature and sunlight, using its NOCT, and the power the panel delivers after the heat loss.
- ElectricityThree-Phase Neutral Current Calculator (Unbalanced Loads)The current that flows in the neutral of a three-phase four-wire supply when the three phase currents are unequal, with the unbalance and the neutral as a share of the largest phase.
- ElectricityTransistor Base Resistor Calculator (Switching)Base resistor that drives a bipolar transistor fully on as a switch, from the drive voltage, the load current and the transistor's gain.
- ElectricityRectangular Waveguide Cut-Off Frequency Calculator (WR-90, TE10)Cut-off frequency of the TE10, TE20, TE01 and TE11 modes of a rectangular waveguide, with the guide wavelength and group velocity at your operating frequency.
- ElectricityZener Diode Resistor CalculatorSeries resistor for a zener voltage regulator, the power the resistor and the zener must handle, from the supply, zener voltage and load current.
- ElectricityBattery Internal Resistance CalculatorInternal resistance of a battery or cell from its voltage with and without a load, with the heat it loses and the current it could deliver into a short.
- ElectricityIlluminance from a Lamp Calculator (Inverse Square and Cosine Law)Light level in lux at any point on a floor, desk or wall below a lamp, from its luminous intensity, height and how far to the side the point is.
- ElectricityLinear Regulator Heat and Heatsink CalculatorHow much heat a linear voltage regulator such as a 7805 or LM317 produces, how hot it gets without a heatsink, and the heatsink rating it needs.
- ElectricityPeukert's Law Battery Runtime CalculatorHow long a battery really lasts at a given current, allowing for the capacity it loses when discharged faster than its rated time.
- ElectricityPT100 / PT1000 RTD Calculator (IEC 60751)Resistance of a platinum PT100 or PT1000 sensor at any temperature, and the temperature that a measured resistance means, using the IEC 60751 equation.