Ohm's Law Calculator – V, I, R and Power

Ohm's Law states V = I × R. It describes the relationship between voltage, current and resistance in a circuit. Published by Georg Ohm in 1827, it is the foundation of circuit analysis.

Power (W) = V × I = I² × R = V² / R. All three formulas give the same result for a given circuit.

In DC, resistance (Ω) is straightforward. In AC, total opposition is impedance (Z) including resistance plus reactance from capacitors and inductors.