Ohm's Law Calculator

Find voltage, current, resistance or power from any two values using Ohm's law.

Quick answer: Ohm's Law Calculator: Find voltage, current, resistance or power from any two values using Ohm's law. Everything runs in your browser, so nothing you enter is uploaded or stored.

Voltage (V), leave 0 if unknown

Current (A), leave 0 if unknown

Resistance (ohms), leave 0 if unknown

How to use Ohm's Law Calculator

Enter your values in the fields.
The results update instantly as you type.
Note or copy the numbers you need.

Features

Instant results
Free, no signup
Runs in your browser, nothing is uploaded
Works on phone and desktop

Formula

V = I x R, I = V / R, R = V / I, P = V x I.

Worked example

With 12 V across 6 ohms the current is 2 A and the power is 24 W.

Frequently asked questions

What is Ohm's law?

Voltage equals current times resistance: V = I x R.

How do I find power?

P = V x I, which also equals I squared x R.

Is the Ohm's Law Calculator free?

Yes. It is free, needs no signup and works on any device.