Ohm's Law Calculator

Ohm's Law states that the voltage across a conductor is proportional to the current flowing through it, with resistance as the proportionality constant: V = IR. Formulated by Georg Ohm in 1827, it is the most fundamental relationship in electrical engineering

The calculator uses the standard published formula for ohms law. Results are accurate to the precision of the inputs you provide. For financial, medical, or legal decisions, always verify with a qualified professional.

This calculator works with inches, watts. You can enter values in the units shown — the calculator handles all conversions internally.

The core formula is: V = IR (voltage = current × resistance). Each step in the calculation is shown so you can verify the result manually.