12 V at 2 A
R = 12 ÷ 2 = 6 Ω, and P = 12 × 2 = 24 W.
Ohm's Law Calculator
Find voltage, current, resistance or power from any two of them with Ohm's law.
Result
Enter your values and select Calculate to see the result.
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How the Ohm's Law Calculator works
Ohm's law links voltage (V), current (I) and resistance (R), and the power formula adds power (P). Enter any two of the four and the calculator finds the other two — for example, current and power from a bulb's voltage and wattage.
Formulas
Ohm's law
V = I × R
Power
P = V × I = I² × R = V² ÷ R
Examples
A 60 W bulb on 120 V
I = 60 ÷ 120 = 0.5 A, and R = 120² ÷ 60 = 240 Ω (hot filament).
Frequently asked questions
Does Ohm's law always apply?
It applies to resistors and wires; LEDs, motors and many electronics aren't simple resistances.
What about AC circuits?
For resistive loads it works with RMS values; for motors, use the Watts, Amps and Volts Converter with a power factor.
What units should I use?
Volts, amps, ohms and watts. Convert milliamps to amps first (20 mA = 0.02 A).
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