kVA to kW Calculator
Commercial and three-phase generators are often rated in kVA, while your loads are measured in kW. This calculator converts between them using power factor, so you can tell what a generator rating means for the equipment you need to run.
kVA to kW Calculator
Convert between apparent power (kVA) and real power (kW) using power factor. Common on standby and commercial generator ratings.
kVA is the total power a generator's alternator must carry; kW is the useful power your loads consume.
Formulas
- kW = kVA × power factor
- kVA = kW ÷ power factor
- Reactive power: kVAR = √(kVA² − kW²)
Example: a generator rated 25 kVA at 0.8 power factor delivers 25 × 0.8 = 20 kW of real power.
kVA, kW and power factor explained
- kW (real power) is the power that does useful work, such as turning a motor, heating an element or lighting a lamp. It is what fuel is burned to produce.
- kVA (apparent power) is volts × amps, the total the alternator and wiring have to carry.
- Power factor is the ratio kW ÷ kVA. Motors and transformers draw some current that does no useful work, so their PF is below 1.
Industrial generator ratings conventionally assume a 0.8 power factor because mixed motor loads in commercial buildings typically fall around there. That is why a “100 kVA” generator is normally an 80 kW generator. Single-phase residential standby generators are usually rated directly in kW at a power factor of 1.0.
kVA to kW conversion table (PF 0.8)
| kVA | kW at 0.8 PF | Amps at 208 V three-phase | Amps at 480 V three-phase |
|---|---|---|---|
| 10 | 8 | 27.8 | 12.0 |
| 25 | 20 | 69.4 | 30.1 |
| 50 | 40 | 139 | 60.1 |
| 100 | 80 | 278 | 120 |
| 150 | 120 | 416 | 180 |
| 250 | 200 | 694 | 301 |
| 500 | 400 | 1,388 | 601 |
Amps = kVA × 1,000 ÷ (√3 × volts). Convert for other voltages with the watts to amps calculator.
Frequently asked questions
Which matters more when sizing a generator, kVA or kW?
Both. The engine must supply the kW, and the alternator must carry the kVA. If your loads have a power factor lower than the generator’s rated PF (for example a lot of motors at 0.7), the alternator can hit its kVA limit before the engine reaches its kW rating.
Is kVA the same as kW for home generators?
For practical purposes, yes. Residential single-phase generators are rated at a power factor of 1.0, so a 22 kW home standby unit is also 22 kVA. Household loads are mostly resistive or power-factor corrected.