kVA to kW Calculator
Convert kilovolt-amperes (kVA) to kilowatts (kW) using the power factor. Essential for correctly sizing generators, UPS systems, and transformers.
Convert kVA to kW
Result
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Real Power (kW)
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Real Power (W)
Formula
kW = kVA × Power Factor
The power factor is a number between 0 and 1. A PF of 1 means all apparent power is real power. A PF of 0.8 means 80% is real power and 20% is reactive power that does no useful work.
Example Calculation
A 15 kVA generator operating at a power factor of 0.8:
kW = 15 kVA × 0.8 = 12 kW (12,000W real power)
This means if you connect purely resistive loads (heaters, lighting), you can draw 12 kW from this generator — not 15 kW.
Common Power Factor Values
- Resistive loads (heaters, incandescent lights): PF = 1.0
- Most generators and UPS: PF = 0.8 (rated)
- Large induction motors: PF = 0.75–0.90
- LED lighting with drivers: PF = 0.90–0.98
- Computers and server racks: PF = 0.90–0.99
- Small induction motors (under full load): PF = 0.50–0.80
Frequently Asked Questions
How do I convert kVA to kW?
Multiply kVA by the power factor: kW = kVA × PF. A 10 kVA generator at PF=0.8 delivers 8 kW of real power. Check the generator or UPS nameplate for its rated power factor.
What power factor should I use?
Generators and UPS systems are typically rated at PF = 0.8. For a mixed load of office equipment and computers, 0.85–0.95 is realistic. For purely resistive loads (space heaters), use PF = 1.0.
Why is kW less than kVA?
kVA is apparent power — what the supply must provide. kW is real power — what gets converted to work or heat. Inductive loads (motors, transformers, fluorescent ballasts) draw reactive current that increases kVA but not kW. Capacitors can correct this.