Ohm's Law Calculator - Voltage, Current, Resistance & Power

Use this Ohm's Law calculator to solve basic circuit problems. Enter any two of the four values – voltage (V), current (I), resistance (R) or power (P) – and the calculator will compute the remaining two.

Ohm's Law and Power in Simple Form

Ohm's Law describes the relationship between voltage (V), current (I) and resistance (R) in a simple DC circuit: V = I × R. Once two of these values are known, the third can be calculated.

Electrical power (P), measured in watts, links to these quantities through:

P = V × I
P = I² × R
P = V² / R

This calculator uses these formulas to solve for the missing values when any two inputs are provided. It is suitable for basic electronics, hobby projects, education and quick circuit estimates.

For high-voltage or safety-critical designs, always rely on professional tools and consult an engineer.