What is the Ohm's Law Calculator?
Solve Ohm's law for voltage, current or resistance, with the power dissipated.
Enter find, voltage, current and resistance and the Ohm's Law Calculator returns answer and power. Results update as you type, and nothing you enter leaves your device.
How it is calculated
V = I × R
I = V ÷ R
R = V ÷ I
P = V × I
How to use it
- Choose find.
- Enter voltage in V.
- Enter current in A.
- Enter resistance in Ω.
- Read answer in the results panel. It updates as you type.
- Change any value to compare scenarios, or use Share to send the result as a link.
Worked example
Common questions
What formula does the Ohm's Law Calculator use?
It uses: V = I × R; I = V ÷ R; R = V ÷ I; P = V × I.
What do I need to use the Ohm's Law Calculator?
You need find, voltage, current and resistance. Sensible starting values are filled in so you can see how it works straight away.
Is the Ohm's Law Calculator free, and is my data stored?
It is free with no sign-up. The calculation runs in your browser, so the values you enter are not sent to or stored on our server.