Ohm's Law Calculator: Voltage, Current, Resistance, and Power (V, I, R, P)

How It Works

Ohm's Law is the fundamental relationship between voltage, current, and resistance in electrical circuits. It's the most important formula every electrician uses daily.

V = I × R

V = Voltage (Volts)
I = Current (Amps)
R = Resistance (Ohms)

P = V × I

P = Power (Watts)

Practical uses: Sizing wires, calculating circuit loads, troubleshooting electrical problems, determining heat dissipation, and verifying safe operating conditions.

How to use: Select what you want to calculate, then enter any two known values. The calculator will find the missing values using Ohm's Law formulas.