Ohm's Law Calculator
Solve voltage, current, resistance, or power.
Enter any two values. The other two are calculated for you.
Fill in any two fields to solve for the rest.
Ohm's Law: V = I × R. Power: P = V × I. From those two you can derive every relationship in this calculator. Negative values for power from V or I squared cases will fail since the square root has no real answer.
About
V = IR. P = VI. Enter any two of voltage, current, resistance, or power and the calculator finds the rest. Standard tool for electronics tinkerers.
How to use
- Enter any two of V, I, R, P.
- See the other two.
FAQ
What are the units?+
Volts, amps, ohms, watts. Toggle to see milliamps, kilo-ohms, etc, for working with electronics circuits.
Does it work for AC circuits?+
For purely resistive AC loads, yes (use RMS voltage and current). For reactive loads (motors, inductors), you need impedance, not just resistance.