About the Ohm's Law Calculator
Solve for voltage, current, resistance, or power from any two known circuit values.
What it is
Ohm's Law (V = IR) relates voltage, current, and resistance in a circuit, and combines with the power formula (P = VI) to describe the full electrical picture. Enter any two of the four quantities and this tool solves for the rest using the correct interlinked formula automatically.
Features
Solve for V, I, R, or P
Automatically picks the correct formula from any valid pair of known values.
Formula triangles
Visual V/I/R and P/V/I triangles highlight which quantity is being solved.
Unit conversion
Mix volts/millivolts, amps/milliamps, and ohms/kilohms/megaohms freely.
Step-by-step working
Every result shows the formula and substitution with your actual entered values.