Ohm's Law Calculator
Enter any two of Voltage, Current, Resistance, and Power — the other two are calculated instantly. Supports all common electronic unit prefixes.
VVoltage
ICurrent
RResistance
PPower
Enter 2 values to calculate the other 2
V
I
R
P
Reference formulas
Ohm's Law relates voltage (V), current (I), and resistance (R) in a circuit. Power (P) follows directly. Enter any two values and the calculator solves for the rest.
V=I×R
I=VR
R=VI
P=V×I=I2×R=V2R
Quick Reference