Calculate voltage, current, or resistance using Ohm's Law. Free online Ohm's Law calculator with power calculation and formula.
Ohm's Law states that the voltage across a conductor is proportional to the current flowing through it, with resistance as the constant of proportionality. This calculator helps you find voltage (V), current (I), or resistance (R) when you know any two of the three values, plus calculates power (P).
V = I × R | I = V / R | R = V / I | P = V × IOhm's Law relates voltage (V), current (I), and resistance (R). Voltage equals current times resistance. Power equals voltage times current. Enter any two known values to calculate the remaining unknowns.
| Input | Output |
|---|---|
| V = 120V, I = 5A | R = 24 Ω, P = 600 W |
| V = 240V, R = 60 Ω | I = 4 A, P = 960 W |
| I = 0.5A, R = 100 Ω | V = 50 V, P = 25 W |