VA to Watts Calculator
Convert apparent power in volt-amps (VA) to real power in watts (W). Enter the apparent power and the power factor, and press Calculate to get the real power in watts using P(W) = S(VA) × PF. Everything runs locally in your browser.
Enter apparent power in volt-amps
Type the apparent power S in volt-amps — the combined real and reactive power a system carries. UPS units, transformers and generators are often rated in VA rather than watts. Scientific notation like 5e-3 is accepted.
Enter the power factor
Type the power factor PF, a number between 0 and 1 that describes how much of the apparent power actually does work. Use 1 for purely resistive loads like heaters; motors and electronics typically sit well below 1. Check the nameplate or measure it for accuracy.
Press Calculate, read watts
Real power appears in watts instantly. Press Reset to clear the fields and start over. Every value is computed in your own browser tab.
How to convert VA to watts
- What is the VA to watts formula?
- The real power P in watts (W) is equal to the apparent power S in volt-amps (VA), times the power factor PF: P(W) = S(VA) × PF.
- Can you give a worked example?
- A 1000 VA load at a power factor of 0.8 delivers P = 1000 × 0.8 = 800 W. At unity power factor the conversion is exact — 1000 VA × 1 = 1000 W — and a power factor of 0 gives 0 W.
- Why are VA and watts different?
- VA is apparent power — the total flow a system must carry. Watts is real power — the part that actually performs work. The power factor (0 to 1) is their ratio, lowered by reactive loads such as motors and transformers, so watts are never more than the VA figure implies.
- What power factor should I use?
- Use 1 only for purely resistive loads. Inductive and electronic loads run below 1 — read the equipment nameplate or measure it with a power analyzer. Do not guess a typical value for anything that needs to be accurate.
Privacy: every calculation runs in your browser tab — no value you type is sent anywhere. Results are ideal-circuit values; verify real installations with a multimeter.