VA to Watts Calculator

Convert VA to watts (or watts to VA) using the power factor — the calculation you need when sizing a UPS or inverter.

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What is the VA to Watts Calculator?

VA (volt-amperes) measures apparent power — what a UPS or inverter's rating actually describes — while watts measure real power, the amount actually doing useful work. The two differ because of the load's power factor: purely resistive loads like heaters and incandescent bulbs have a power factor near 1 (VA ≈ watts), while motors, fans and switch-mode power supplies have a lower power factor (often 0.6–0.9), meaning their wattage is noticeably less than their VA rating.

How to Calculate

Enter the VA rating (or wattage) and the power factor of your load — check the appliance label or use a typical value for the load type if it isn't specified. Watts = VA × power factor, and conversely VA = Watts ÷ power factor; this matters most when sizing a UPS or inverter, since its VA capacity — not the wattage alone — determines how much load it can safely support.

Formula

W = VA × PF · VA = W ÷ PF

How to Use

  1. Enter a value and pick the units.
  2. The converted result updates instantly.
  3. Use Copy or Print to save it.

Frequently Asked Questions

Why is my UPS rated in VA?
UPS and inverter makers rate apparent power (VA) because it does not depend on the load type. At a typical 0.8 power factor, a 1000 VA UPS supports roughly 800 W of load.
What power factor should I assume?
0.8 is the common default for UPS ratings; use the actual figure if your equipment specifies it.
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