About the Watts to VA Calculator
This calculator converts W to VA. W is one joule of energy per second, the basic unit of power printed on bulbs, chargers and appliances, and VA is volt-amperes, the apparent power that a supply must deliver, which is voltage times current without regard to power factor. It divides the watts by the power factor, and also shows the same figure in kVA. Enter your figures and the answer appears at once, together with a few related values, and you can copy the result with one tap. The sums are done in your browser and nothing is sent anywhere.
Updated October 2026
How to use the Watts to VA Calculator
- 1Enter the value in W.
- 2Fill in the other boxes that the W to VA calculation needs, such as time, voltage or power factor.
- 3Read the answer in the large result box.
- 4Check the extra rows for related values.
- 5Press Copy result to keep it.
When you need W to VA
When you buy a UPS or an inverter, the sticker may show both VA and watts, and the VA figure is larger. To see whether a unit can carry your equipment, convert the watts of your loads into VA with the power factor of the load, and compare it to the VA rating.
Computers with modern power supplies have a power factor near 0.9 to 1, while older motors and fluorescent lights are lower. Use the figure for your load. If you do not know it, 0.8 is a common cautious choice.
How the W to VA sum works
VA = watts ÷ power factor. A load of 800 W at a power factor of 0.8 needs a supply rated at 800 ÷ 0.8 = 1,000 VA.
The displayed answer is rounded to six significant figures, but the sum itself is not rounded, so converting W to VA and back again gives you the number you started with.
- Compare both VA and W ratings
- Use the load's power factor
- Leave headroom
Mistakes to avoid when converting W to VA
Do not compare watts with the VA rating directly. A 1,000 VA unit may only supply 600 W. Check both numbers: your load in watts must fit under the unit's watt rating, and the same load in VA under its VA rating.
On phone and computer
On a phone, type in the boxes one after another and read the VA result underneath; the Copy button puts it on the clipboard for a message or a note. On a computer the inputs sit on the left and the answer on the right, so you can change one figure and watch the VA value move. The W to VA page works the same on both. The power factor decides the gap, so find it with Power Factor Calculator. VA to Watts Calculator reverses the step, Watts to kVA Calculator gives larger numbers, and kW to VA Calculator is the kilowatt version.
Features
- W to VA in one step
- Related values shown with the answer
- Clear messages for impossible inputs
- Copy the result with one tap
- Private: nothing is uploaded
- Works on phone and computer
Frequently asked questions
How do I convert W to VA?
VA = watts ÷ power factor. A load of 800 W at a power factor of 0.8 needs a supply rated at 800 ÷ 0.8 = 1,000 VA.
What is the formula for W to VA?
VA = watts ÷ power factor. The calculator applies it exactly and rounds only the displayed answer.
What is the difference between W and VA?
W is one joule of energy per second, the basic unit of power printed on bulbs, chargers and appliances. VA is volt-amperes, the apparent power that a supply must deliver, which is voltage times current without regard to power factor. They measure different things, which is why converting from W to VA needs more than a simple multiplication in some cases.
How many VA is 500 watts?
At a power factor of 0.8, 500 ÷ 0.8 = 625 VA. At a power factor of 1, it is 500 VA.
Why is VA larger than watts?
Because VA is the apparent power, which includes the reactive part. VA equals watts only when the power factor is exactly 1.
Is this W to VA calculator free and private?
Yes. It is free, needs no account, and runs in your browser, so the figures you type are not uploaded or stored. It is meant for planning and learning; for wiring or safety work, check the result against your equipment's rating plate and local rules.