Ohm's law calculator
Calculate voltage, current, resistance and power using Ohm's law - enter the two known values.
Power (P)
36 W
Voltage (V)12 V
Current (I)3 A
Resistance (R)4 Ω
Power (P)36 W
Calculations are based on Estonia's tax rates in force for 2026. Results are informational.
Last updated: 2026-06-03
What is Ohm's law?
Ohm's law relates voltage, current and resistance: U = I × R. Power is P = U × I. Knowing two values, you can find the rest.
How it is calculated
Formula
Ohm's law U = I × R (voltage = current × resistance). Power P = U × I. Given any two values, the rest are derived.
Example
U = 12 V, R = 4 Ω → I = 3 A, P = 36 W.
Frequently asked questions
What is Ohm's law?+
Ohm's law relates voltage, current and resistance: U = I × R. Given any two, you can compute the third.
How do I calculate power?+
Power is P = U × I, that is voltage multiplied by current.