Electrical Power Calculator
Calculate DC electrical power from voltage and current.
Formula
For DC circuits, P = VI.
What Is Electrical Power?
Electrical power is the rate at which electrical energy is transferred or converted. In a DC circuit, multiplying voltage by current gives power in watts.
Example Calculation
A 12 V device drawing 3.5 A uses 12 × 3.5 = 42 W.
Factors and Interpretation
Power rises when either voltage or current rises. This simple formula is appropriate for DC loads and resistive calculations. AC circuits with phase shift require power factor, so the AC Power Calculator is more appropriate there.
Frequently Asked Questions
Is P = VI valid for AC circuits?
It gives apparent power for RMS values unless power factor is included. Use the AC tool for real power.
How many watts is 1 amp?
It depends on voltage. At 12 V, 1 A equals 12 W; at 230 V, 1 A equals 230 W for a unity-power-factor load.
Can I calculate current from watts?
Yes. Rearranging the formula gives I = P/V.
Related Tools
Formula and Practical Limits
For DC circuits, electrical power is P = VI. AC real power can also depend on phase and power factor, so multiplying RMS voltage and current alone may give apparent rather than real power.