Power Factor Calculator
Fill in any two of kW, kVA and power factor, and leave the third blank.
This result is an estimate only. Double-check important figures before relying on them.
How it is calculated
- Power factor = kW ÷ kVA
- kW = kVA × power factor, and kVA = kW ÷ power factor
- Reactive power = √(kVA² − kW²)
For the current drawn, use the amps to kW converter.
Worked example
A load drawing 80 kW from 100 kVA:
- Power factor = 80 ÷ 100 = 0.8
- Reactive power = √(10,000 − 6,400) = 60 kVAr
Why your number may differ
This treats the values as a steady load. Real loads vary through the day, and capacitor banks, if fitted, change the power factor.
Frequently asked questions
What is power factor?
The share of the power a load draws that does useful work. It is real power (kW) divided by apparent power (kVA), between 0 and 1.
Why does a low power factor matter?
It means more current for the same useful power, which wastes energy in cables and can lead to extra charges for some commercial customers.
What is reactive power?
The part of the supply that swings back and forth without doing work, measured in kVAr. kVA² = kW² + kVAr².