Ohm's Law Calculator
Solve Ohm's law: enter any two of voltage, current, resistance or power and get the rest. Free electronics calculator.
Enter any two values and leave the other two blank — the calculator solves for all four.
Frequently asked questions
- What is Ohm's law?
- Voltage equals current times resistance (V = I×R). Power adds P = V×I. With any two of the four quantities, the other two follow.
- Why does it say leave one blank?
- Each formula pair uses exactly two knowns. Entering three makes the system over-determined, so the tool asks for two.
- Does it work for AC circuits?
- Only for DC or purely resistive AC. Reactance and phase angle in real AC loads change the relationship.
This tool runs entirely in your browser. No data is uploaded anywhere.