Case 1
- Real power (kW)
- 8kW
- Power factor
- 0.8
10.00kVA
Open with these valueskW to kVA Calculator
10.00kVA
Result: 10.00 kVADivide, do not multiply: kVA = kW ÷ PF. An 8 kW load at a power factor of 0.8 needs 10 kVA of supply. The worse the power factor, the more kVA the same kilowatts demand — at 0.5 the same 8 kW would need 16 kVA, which is why generators are rated in kVA.
Worked examples
Case 2
- Real power (kW)
- 45kW
- Power factor
- 0.9
50.00kVA
Open with these valuesCase 3
- Real power (kW)
- 21.25kW
- Power factor
- 0.85
25.00kVA
Open with these valuesHow it's calculated
kVA = kW ÷ PF
- StepEnter the real power of the load in kilowatts.
- StepEnter the power factor of the load, between 0 and 1.
- ResultRead the apparent power in kVA — the rating a generator or UPS has to cover.
Reference table
| kW, PF | Reactive power | Apparent power in kVA |
|---|---|---|
| 8, 0.8 | 6.00 kVAR | 10.00 |
| 14.25, 0.95 | 4.68 kVAR | 15.00 |
| 21.25, 0.85 | 13.17 kVAR | 25.00 |
| 45, 0.9 | 21.79 kVAR | 50.00 |
| 100, 1 | 0.00 kVAR | 100.00 |
Questions
How do I convert kW to kVA?
Divide the real power in kilowatts by the power factor. An 8 kW load with a power factor of 0.8 has an apparent power of 8 ÷ 0.8 = 10 kVA. At a power factor of 1, a purely resistive load, kVA equals kW exactly.
What is the power factor?
It is a number between 0 and 1 describing how efficiently a load turns apparent power into real work. Resistive loads such as heaters sit at 1. Motors, compressors and switching supplies usually fall between 0.7 and 0.95, because they also draw reactive current for their fields.
Why are generators and transformers rated in kVA, not kW?
They have to carry the full current the load draws, including the reactive part, and their thermal limit follows that total current. Rating them in kVA makes it possible to match a machine to any load without knowing every device's power factor.
What is reactive power in kVAR?
It is the part of the apparent power that oscillates between source and load without doing useful work, kVAR = √(kVA² − kW²). It maintains the magnetic fields in motors and transformers. Correction capacitors reduce it and lower the kVA demand.
Which power factor should I enter?
Use the value on the nameplate or data sheet. For a mixed load whose combined factor is unknown, 0.8 covers general industrial equipment, 0.9 a well-optimised motor system and 1 a purely resistive load. When in doubt take 0.8, because the higher kVA figure keeps the margin on the safe side.
Sources and last check
Information, not professional advice.