kW to kVA Calculator
Convert kilowatts (real power) to kilovolt-amperes (apparent power) using the power factor. The formula is kVA = kW / Power Factor. This conversion is essential for sizing generators, transformers, and UPS systems.
How to Convert kW to kVA
- Determine the real power in kilowatts (kW).
- Determine the power factor of the load (typically 0.7-0.95).
- Divide kW by the power factor to get kVA.
- The result is the apparent power the system must supply.
Formula
kVA = kW / Power Factor
kVAR = sqrt(kVA² - kW²)
Power Factor = kW / kVA
Example Calculation
A facility uses 10 kW with a power factor of 0.8:
kVA = 10 kW / 0.8 = 12.5 kVA
kVAR = sqrt(12.5² - 10²) = sqrt(156.25 - 100) = sqrt(56.25) = 7.5 kVAR
The generator or transformer must be rated for at least 12.5 kVA to supply this 10 kW load.
kW to kVA Reference Table
| Real Power | Power Factor | Apparent Power |
|---|---|---|
| 5 kW | 0.7 | 7.14 kVA |
| 5 kW | 0.8 | 6.25 kVA |
| 5 kW | 0.9 | 5.56 kVA |
| 10 kW | 0.7 | 14.29 kVA |
| 10 kW | 0.8 | 12.50 kVA |
| 10 kW | 0.9 | 11.11 kVA |
| 20 kW | 0.8 | 25.00 kVA |
| 50 kW | 0.8 | 62.50 kVA |
| 100 kW | 0.8 | 125.00 kVA |
Frequently Asked Questions
What is the difference between kW and kVA?
kW (kilowatts) is real power that does actual work. kVA (kilovolt-amperes) is apparent power, which includes both real power and reactive power. In a purely resistive load, kW equals kVA.
Why is kVA always greater than or equal to kW?
Because power factor is always between 0 and 1, dividing kW by PF always gives a value equal to or greater than kW. The difference represents reactive power consumed by inductive or capacitive loads.
What is reactive power (kVAR)?
Reactive power (kVAR) is the power that oscillates between the source and reactive components (inductors, capacitors). It does no useful work but is required to maintain voltage and magnetic fields.
How do I choose the right generator size?
Generators are rated in kVA. Calculate your total kW load, divide by the expected power factor, and add 20-25% safety margin. For example, 10 kW at PF 0.8 needs at least a 15-16 kVA generator.
What is a typical power factor for commercial buildings?
Commercial buildings typically have a power factor of 0.8-0.9. Industrial facilities with many motors may have PF as low as 0.7. Power factor correction capacitors can improve PF to 0.95+.