Ohm's Law Calculator
Solve for voltage, current, resistance, or power — enter any two values and get the other two.
Voltage–
Current–
Resistance–
Power–
Ohm's Law and power
V = I × R
P = V × I = I² × R = V² / R
Ohm's Law links voltage (V, volts), current (I, amps), and resistance (R, ohms); the power law adds power (P, watts). Knowing any two of the four quantities is enough to find the other two. Enter the two you know and the calculator fills in the rest.
Worked example
With 5 V across a 1 kΩ resistor: current is 5 V ÷ 1000 Ω = 5 mA, and power is 5 V × 5 mA = 25 mW.