Ohm's Law Calculator
Calculate voltage, current, resistance, or power using Ohm's law. Enter any two values to find the other two.
Enter any two values to calculate the rest.
Enter any two values.
Ohm's Law Formulas
V = I × R
I = V / R
R = V / I
P = V × I = I²R = V²/R
I = V / R
R = V / I
P = V × I = I²R = V²/R
Example: 12 V, 4 Ω resistor.
I = 12 / 4 = 3 A
P = 12 × 3 = 36 W
I = 12 / 4 = 3 A
P = 12 × 3 = 36 W
Ohm's Law Wheel
The Ohm's law wheel shows all 12 formulas relating V, I, R, and P. Knowing any two quantities lets you calculate the other two.
FAQ
Does Ohm's law apply to AC circuits?
For purely resistive loads, yes. For circuits with capacitors or inductors, you need to use impedance (Z) instead of resistance (R).
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Last updated: 2026-08-08