Ohm's Law states V = IR: voltage equals current times resistance. Combined with P = IV, you can solve for any of the four quantities.

How do I calculate power using Ohm's Law?

P = IV = V²/R = I²R. Power is measured in watts (W).

Does Ohm's Law work for AC circuits?

Ohm's Law applies to resistive AC circuits. For circuits with capacitors/inductors, use impedance (Z) instead of resistance.

Calculate voltage, current, resistance, and power using Ohm's Law. Supports AC and DC circuits with power factor.

Use the full interactive calculator below, or

Resistor Color Code

Electrical