Power Factor Calculator
Calculate power factor and phase angle from real power in kW and apparent power in kVA. Formula, worked example and typical values.
Try your own numbers
Estimate only. Not engineering or safety advice. Check the result against the applicable standard and the equipment data, and have a competent engineer review it before it is relied on. Terms of use.
Open in the calculator with these values
Formula
Worked example
| Input | Value |
|---|---|
| Real power | 80 kW |
| Apparent power | 100 kVA |
- pf = 80 kW / 100 kVA = 0.8
- φ = arccos(0.8) = 36.87°
Typical values
| Real power (kW) | Power factor | Phase angle (degrees) |
|---|---|---|
| 50 | 0.5 | 60 |
| 60 | 0.6 | 53.13 |
| 70 | 0.7 | 45.57 |
| 80 | 0.8 | 36.87 |
| 90 | 0.9 | 25.84 |
| 100 | 1 | 0 |
Other inputs are the same as in the worked example above.
Assumptions
- Sinusoidal waveforms
Below about 0.9 many utilities apply a penalty; check your tariff.
Frequently asked questions
How is Power Factor calculated?
pf = P / S; φ = arccos(pf). Worked example: Real power 80 kW, apparent power 100 kVA gives Power factor: 0.8 · Phase angle: 36.87°.
What do I need to enter?
Enter real power and apparent power. Change the unit of a value with its selector and the result stays the same.
What is a good power factor?
Closer to 1 is better. Below about 0.9 many utilities charge a penalty, so check your tariff.
How do I improve a low power factor?
Capacitors are commonly used to correct a lagging power factor. The Power Factor Correction calculator in Elecmetric sizes the capacitor bank.
How accurate are the results?
Every figure comes from the same tested engine as the Elecmetric calculators and is meant for estimating. Check design values against the standard and the equipment data you work to.
Related
Next steps in a design: Power Factor CorrectionWatts to kVA
Also see: Power
Formula guides: Power Factor and the Power TrianglePower Factor Correction Payback Formulas
All 78 conversionsPower Factor in Elecmetric