Ohm's Law Calculator

Enter any two of voltage, current, and resistance to instantly calculate the third. A free online Ohm's Law calculator based on V=IR.

Frequently Asked Questions

What is Ohm's Law?
Ohm's Law states that voltage (V) equals current (I) multiplied by resistance (R): V = I × R. It was formulated by Georg Ohm in 1827 and is fundamental to electrical circuits.
Can this calculator compute power (watts)?
Yes. When voltage and current are known, power is calculated as P = V × I. The formulas P = I²R and P = V²/R are also used.
Does Ohm's Law apply to all circuits?
Ohm's Law applies to linear (ohmic) components where resistance is constant. It does not directly apply to nonlinear devices like diodes or transistors.
2026 physical constants