Electricity Calculator

  • Miles Per kWh Calculator
    Calculate your electric vehicle's efficiency in miles per kWh. Enter miles driven and kWh used to get mi/kWh, kWh/100mi, and Wh/mile instantly.
  • Kilowatts to Amps Calculator
    Convert kilowatts (kW) to amps for DC, single-phase and three-phase AC circuits. Enter power, voltage and power factor to get current in amperes.
  • Horsepower to Amps Calculator
    Convert horsepower (HP) to amps for DC, single-phase, and three-phase motors. Enter voltage, efficiency, and power factor to get current draw in amps.
  • Amps to Watts Calculator
    Convert amps to watts for DC, AC single-phase and three-phase circuits. Enter current, voltage and power factor to get watts and kilowatts instantly.
  • Total Harmonic Distortion (THD) Calculator
    Calculate Total Harmonic Distortion (THD) from the fundamental and harmonic amplitudes. Get THD as a percentage and ratio instantly with this free tool.
  • PCB Trace Resistance Calculator
    Calculate PCB copper trace resistance from length, width, copper weight and temperature using R = rho*L/A with temperature correction.
  • Pi Attenuator Calculator
    Calculate Pi attenuator resistor values (series R1 and two shunt R2) for any attenuation in dB and characteristic impedance. Free RF pad designer.
  • Op-Amp Gain Calculator
    Calculate operational amplifier voltage gain for inverting and non-inverting configurations from Rf and Rin, plus gain in decibels (dB).
  • LM317 Resistor Calculator
    Calculate the LM317 adjustable regulator output voltage from R1, R2, reference voltage and adjustment current using Vout = 1.25(1 + R2/R1) + Iadj·R2.
  • Duty Cycle Calculator
    Calculate duty cycle as a percentage from pulse on time and total period. Get off time and signal frequency instantly for any PWM or square wave.
  • Battery Size Calculator
    Calculate the battery capacity (mAh) you need from load current, runtime, and efficiency. Free, instant battery size estimator for projects and devices.
  • Battery Life Calculator
    Estimate how long a battery lasts from its capacity (mAh), the device load current (mA), and an efficiency factor. Instant runtime in hours and days.
  • Battery Capacity Calculator
    Convert battery capacity from mAh to watt-hours (Wh). Enter mAh and voltage to instantly find energy in Wh, kWh, and charge in Ah.
  • Magnetic Flux Density Unit Conversion Calculator
    Convert magnetic flux density (magnetic induction B) between Gauss, Tesla, Weber and Maxwell units instantly. Enter one value and see all 12 units.
  • Electrical Resistance Unit Conversion Calculator
    Convert electrical resistance between picoohm, nanoohm, microohm, milliohm, ohm, kiloohm, megaohm, gigaohm, abohm and volt per ampere instantly.
  • Joule Heating Calculator
    Calculate Joule heating (resistive heat) with Q = I²Rt. Enter current, resistance and time to find heat in joules, power in watts, and kilocalories.
  • Watts to Heating Time Calculator
    Calculate how long a heater of a given wattage takes to warm water. Enter mass, power, temperatures and efficiency to get heating time and energy.
  • Water Heating Energy Calculator
    Calculate the energy needed to heat water using Q = m·c·ΔT. Enter volume, start/end temperature and efficiency to get kWh, kJ and joules.
  • RC Filter Cutoff Frequency Calculator
    Calculate the −3 dB cutoff frequency of an RC low-pass or high-pass filter from resistance and capacitance using f = 1/(2πRC), plus time constant.
  • LC Filter Cutoff Frequency Calculator
    Calculate the resonant cutoff frequency of an LC filter from inductance and capacitance using f = 1 / (2π√(LC)). Fast and accurate.
  • Ohm's Law Power Calculator
    Calculate electrical power (watts) from voltage and current using Ohm's law: P = V × I. Also shows resistance. Fast, free online tool.
  • Noise Figure Calculator
    Calculate noise figure (NF in dB) from input/output SNR or cascade noise factor using the Friis equation for two RF stages with gain and NF in dB.
  • Capacitor Size Calculator
    Calculate the capacitor size you need from charge and voltage (C = Q/V) or for power-supply ripple smoothing (C = I/(f × Vripple)). Results in F, µF, nF.
  • Forward Converter Calculator
    Calculate the output voltage of a forward converter from input voltage, transformer turns ratio (Ns/Np), and duty cycle D using Vout = Vin × (Ns/Np) × D.

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