Electrical Calculators
Ohm’s law, power, voltage drop, resistors and electricity cost for electricians, students and DIYers.
- Ohm's Law CalculatorSolve Ohm's law and the power formulas: enter any two of voltage, current, resistance and power to get the other two,…
- Watts, Volts and Amps CalculatorConvert watts to amps and amps to watts for DC, single-phase and three-phase AC circuits with power factor, plus kVA,…
- Voltage Drop CalculatorCalculate voltage drop for copper or aluminum wire in single-phase, DC or three-phase circuits by AWG size, length and…
- Electrical Box Fill CalculatorCalculate electrical box fill volume under NEC 314.16(B): conductors, devices, clamps and grounds, compared with the…
- Breaker Size CalculatorFind the minimum breaker size for a load: continuous loads at 125%, rounded up to the next standard breaker rating from…
- Transformer Size CalculatorCalculate the kVA rating needed for a single-phase or three-phase transformer from load current or kW, rounded up to a…
- Generator Size CalculatorEstimate the generator size you need from the running watts of your appliances plus the largest motor’s starting surge.
- Series and Parallel Resistor CalculatorCalculate total resistance of resistors in series or parallel, with current, voltage and power in each resistor when…
- Resistor Color Code CalculatorDecode 4, 5 and 6 band resistor color codes to resistance, tolerance and temperature coefficient, or find the colors…
- RC Time Constant CalculatorCalculate the RC time constant (tau) of a resistor and capacitor, the time to charge or discharge, the voltage at any…
- LED Resistor CalculatorCalculate the series resistor for an LED or string of LEDs from supply voltage, forward voltage and current, with the…
- Battery Life CalculatorEstimate battery run time from capacity in mAh, Ah or Wh and the load in mA, amps or watts, with usable capacity for…
- Battery Bank Size CalculatorSize a battery bank in amp-hours and kWh from daily energy use, days of backup, system voltage, depth of discharge and…
- Solar Panel Size CalculatorEstimate how many solar panels and what system size you need from your monthly electricity use and local peak sun hours.
- Inverter Size CalculatorSize a power inverter from the continuous watts of your loads, the largest surge, and a safety margin, with DC input…
- Electricity Cost CalculatorEstimate the electricity cost of an appliance from its watts and hours of use, or estimate a monthly bill from kWh used.
- Power Factor Correction CalculatorCalculate the capacitor kVAR needed to correct power factor, the kVA and current before and after, and capacitance in…