Volts to Watts Calculator
Enter voltage, current and power factor to get real, apparent and reactive power.
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Formula
watts = volts × amps × power factorVA = volts × ampsvar = VA × √(1 − power factor²)
Worked example
230 V, 8 A, power factor 0.85:
- Apparent power: 230 × 8 = 1840 VA
- Real power: 1840 × 0.85 = 1564 W
- Reactive power: 1840 × √(1 − 0.7225) = 969.28 var
120 V and 15 A at power factor 1 gives 1800 W.
Frequently asked questions
How do I convert volts to watts?
Volts alone cannot give watts; you also need current. Watts = volts × amps × power factor. At 120 V and 15 A with PF 1 that is 1800 W.
What power factor do I enter for a DC circuit?
Use 1. DC has no phase shift, so watts is simply volts × amps: 12 V × 0.5 A = 6 W.
What are apparent and reactive power?
Apparent power S = V × I in VA. Reactive power Q = S × √(1 − PF²). At 230 V, 8 A, PF 0.85: S = 1840 VA, P = 1564 W and Q = 969.28 var.
Does this work for three-phase?
This page is for a single circuit. For three-phase line-to-line voltage use the amps to watts calculator, which includes the √3 factor. This calculator is for learning and design checks only. It is not a safety certification: wiring, breaker and cable sizing must follow your local electrical code and be checked by a qualified electrician.