kVA to kW Calculator
Convert apparent power to real power, and size a generator or inverter
Real Power
- 1Choose the directionkVA → kW or kW → kVA
- 2Enter the valueAnd the power factor
- 3See the resultPlus a sizing margin
kVA vs kW
kW is the real power that does work; kVA is the total (apparent) power the supply must deliver. Power factor links them.
kW = kVA × power factor
kVA = kW ÷ power factor · kVAR = √(kVA² − kW²)
Sizing a generator or UPS
Generators are rated in kVA at a power factor of 0.8, so a 10 kVA DG set delivers about 8 kW. Add up your load in kW, divide by 0.8, and add 20–25% for motor starting currents and future needs.
Home inverters
Home inverters are rated in VA; their usable watts are usually 0.7–0.8 of the VA rating. A 1,000 VA inverter supports roughly 700–800 W of load.
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Frequently asked questions
How many kW is 1 kVA?
At a power factor of 0.8, 1 kVA = 0.8 kW. At PF 1 (purely resistive loads), 1 kVA = 1 kW.
What size generator do I need for 8 kW?
8 ÷ 0.8 = 10 kVA, so a 12.5 kVA set gives a sensible margin, especially if you have motors or ACs.
Why is kVA higher than kW?
Motors and electronics draw some current that doesn't do useful work (reactive power). The supply must still provide it, so kVA ≥ kW.
Last reviewed: October 2026