VA to Watts Calculator

Convert volt-amps (apparent power) to watts (real power) using power factor. For UPS sizing and electrical loads.

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Formula

Watts = VA × Power Factor — VA is apparent power (V×A), watts is real power; PF is the efficiency ratio between them

Examples

InputResult
1000 VA at PF 0.8800 W
1500 VA at PF 1.01500 W
600 VA at PF 0.6360 W

Frequently Asked Questions

What is the difference between VA and watts?

VA (volt-amps) is apparent power — what the wiring must carry. Watts is real power — what actually does work. Their ratio is the power factor.

What power factor should I use?

Modern computer PSUs with active PFC: 0.95–1.0. Typical motors: 0.6–0.8. Resistive heaters: 1.0. UPS ratings use VA, so divide by your equipment's PF to compare.

Why do UPS units use VA?

Because the UPS must supply the current (heat in wires) regardless of power factor. A 1000 VA / 800 W UPS can deliver 1000 VA but only 800 real watts at PF 0.8.

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