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Electrical Power Calculator

Compute electrical power from V, I, and R in any combination.

Inputs
Enter your values below.
Result
Your answer appears here.

Enter values and press Calculate — the result appears here.

How it works
The formula behind this calculator.

DC: P = V × I; AC single-phase: P = V × I × cos(φ)

V
Voltage
I
Current
cos(φ)
Power factor, 0–1

DC power is volts times amps. AC power includes the power factor — the ratio of real to apparent power. Industrial loads (motors, transformers) have PF < 1.

Example: 120V × 5A at PF 0.9 = 540 W

Ref: IEEE 1459 (Power Definitions)

Tips
  • 💡 P = V × I (DC). P = V × I × cos(φ) for AC single-phase.
  • 💡 Watts and VA differ by the power factor. 1 kVA = 0.8 kW at PF 0.8.

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