Power Factor Calculator
Power factor relates real power to apparent power and indicates how effectively electrical power is converted to useful work under the conventional AC power model.
How to use this calculator
- Enter real power in kW and apparent power in kVA measured for the same load and interval.
- Check that all inputs use the same units, period and population scope.
- Change one assumption at a time when comparing scenarios.
Formula used by power factor calculator calculator
Power factor = real power P ÷ apparent power S. For a sinusoidal system, reactive power Q = √(S² − P²).
- Power factor = real power P ÷ apparent power S. For a sinusoidal system, reactive power Q = √(S² − P²).
- The reactive-power calculation assumes a sinusoidal power triangle. Harmonic distortion and measurement details can change the correct interpretation.
- The tool validates inputs and rounds displayed figures for readability; it does not validate assumptions against external records.
Worked examples
Worked example
A load draws 7.5 kW real power and 10 kVA apparent power.
Power factor = 7.5 ÷ 10 = 0.75.
Power factor is 0.75 under the entered values.
Understanding the result
Power factor relates real power to apparent power and indicates how effectively electrical power is converted to useful work under the conventional AC power model.
The reactive-power calculation assumes a sinusoidal power triangle. Harmonic distortion and measurement details can change the correct interpretation.
Important notes
The reactive-power calculation assumes a sinusoidal power triangle. Harmonic distortion and measurement details can change the correct interpretation.
Treat the result as an estimate from the entered assumptions. For commercial, statistical, engineering or health-related decisions, verify relevant specifications and professional guidance.
Frequently asked questions
Can power factor exceed 1?
No for the real-to-apparent ratio under standard definitions; this tool rejects real power above apparent power.
Does a low factor always mean a faulty appliance?
No. Load type, operating point and system characteristics affect it.
How should I interpret this result?
The reactive-power calculation assumes a sinusoidal power triangle. Harmonic distortion and measurement details can change the correct interpretation.
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This page provides a calculation tool plus explanatory information so you can understand what the result means and when the underlying method may not fit your situation.