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Ohm's Law Calculator

Free Ohm's Law calculator. Find voltage, current, or resistance using V = I × R. Leave one field blank.

V = I × R | I = V / R | R = V / I
Power: P = V × I = I² × R = V² / R

V = I × R — Voltage equals current multiplied by resistance.

Enter any two known values and leave the unknown field empty.

The calculator will solve for the missing value and also show power in watts.

What is Ohm's Law? ▼

Ohm's Law states that voltage (V) equals current (I) times resistance (R): V = I × R. It was discovered by German physicist Georg Ohm in 1827.