Electrical Power Calculator

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Calculates electrical power using voltage, current, and resistance, based on the formulas P=VI, P=I²R, and P=V²/R.

How To Use

How to use this calculator

Start with your values, or try a preset.

Step 1

Enter Voltage (V), Current (I), and Resistance (R) in the units shown.

Step 2

Read Power (P = V²/R), Power (P = I²R), and Power (P = VI) in the results panel. Results update as you change the inputs.

Step 3

Choose a preset to load an example, then adjust the values for your situation.

Worked Examples

See the inputs and their calculated results.

Voltage (V): 12 V; Current (I): 2 A; Resistance (R): 10 Ω

Power (P = V²/R): 14.4 W; Power (P = I²R): 40 W; Power (P = VI): 24 W

Voltage (V): 120 V; Current (I): 5 A; Resistance (R): 24 Ω

Power (P = V²/R): 600 W; Power (P = I²R): 600 W; Power (P = VI): 600 W

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