Power Factor Calculator
A low power factor wastes energy and can add surcharges to your electricity bill. This free calculator finds the power factor of your load from kW, kVA, voltage and current — and sizes the capacitor (kVAR) needed to correct it toward your target.
Power factor correction
Result
| Power factor (cos phi) | |
|---|---|
| Phase angle | |
| Real power | |
| Apparent power | |
| Reactive power |
Capacitor correction
| Required capacitor (kVAR) | |
|---|---|
| Capacitance |
Formula: Qc = P × (tanφ1 − tanφ2), then C = Qc ÷ (2πfV²). Always use a capacitor rated above the voltage and have an electrician install it.
How to use
- Enter the known values of your load (kW/kVA or V/A/PF).
- For correction, enter the current PF, target PF, load and voltage.
- Press "Calculate" — you will get the PF, kVAR and capacitor size.
Tips
- Most utilities penalize a power factor below about 0.85 to 0.9 — correction can pay for itself.
- Measure under your normal load; a correction sized for peak load can overcorrect at light load.
- Have an electrician install the capacitor bank — mains wiring is not a DIY job.
The closer PF is to 1, the better. With a low PF, the power company may add a surcharge — confirm rates on the official website.