Power Factor Calculator
Calculate power factor from real, reactive and apparent power for single or three phase loads with this free electrical calculator online.
Enter Values
Minimum 0
Minimum 0
How to use this calculator
- Enter the real power (kW) and apparent power (kVA).
- Read the power factor.
How it works
Power factor = kW ÷ kVA.
Worked example
8 kW from 10 kVA. = 0.8 power factor.
Common mistakes
- Swapping kW and kVA.
- Forgetting power factor is between 0 and 1.
Frequently asked questions
What is a good power factor?
Close to 1.0 is ideal. Below about 0.9 many utilities apply a penalty, since low power factor wastes supply capacity.
How is power factor calculated?
Power factor = real power (kW) ÷ apparent power (kVA), which equals the cosine of the phase angle between voltage and current.
Why does power factor matter?
A low power factor means more current for the same useful power, which can mean bigger cables and utility penalties.
Related tools
- kVA to kW Calculator
- Three Phase Power Calculator
- Amps to Watts Calculator
- Watts to Amps Calculator
- Reactive Power (kVAR) Calculator
- Single Phase Power Calculator
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Cite this tool
Zerdly. (2026). Power Factor Calculator. Retrieved from https://www.zerdly.com/tools/power-factor-calculator/
Tip: Enter any known values to calculate the remaining results.
All calculations run in your browser. Your inputs are never saved or transmitted.