Ohm's Law & Power Calculator
Lock any two known values (V, I, R, P) — the other two are solved instantly.
Enter any two known values and click their label to lock them. The other two are solved automatically.
Select 2 more value(s) to lock by clicking the label.
Frequently Asked Questions
What is Ohm's law?+
Ohm's law states V = I × R. Voltage (V) equals current (I) times resistance (R). Combined with P = V × I, all four quantities can be derived from any two.
How do I use this calculator?+
Click two field labels to lock them, then type your known values. The remaining two fields are solved automatically.