Power Factor Correction Calculator (kVAR)
Size a capacitor bank to avoid power-factor penalties.
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Power Factor Correction Calculator (kVAR) by TheCalcTools
How the Power Factor Correction Calculator (kVAR) works
Enter the real power in kW and the present and target power factors.
The reactive power to cancel is kW × (tan φ₁ − tan φ₂).
The tool also shows how much line current and kVA are freed.
The formula
Worked example
Using the default values shown in the calculator:
| Load (kW) | 100 |
|---|---|
| Present power factor | 0.75 |
| Target power factor | 0.95 |
| Line voltage (V) | 400 |
- kVAR = 100 × (tan(acos 0.75) − tan(acos 0.95)) = 55.3.
- Current falls from 192.5 A to 151.9 A (21.1% less), releasing 28.1 kVA.
Result:
| Capacitor required (kVAR) | 55.3 |
|---|---|
| Current before (A) | 192.5 |
| Current after (A) | 151.9 |
| Current reduction | 21.1% |
| kVA released | 28.1 |
Frequently asked questions
Why correct the power factor?
Utilities may charge a penalty below a threshold. A higher power factor reduces current, losses and the kVA demand on transformers and generators.
Any caution with capacitors?
Capacitors with harmonic-rich loads can resonate. Use detuned reactors where harmonics are present and automatic switching for varying loads.
Sources and further reading
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This calculator gives estimates for planning only. Electrical installations must be designed, checked and carried out by qualified personnel following local codes and the equipment manufacturer's data. Never rely on this result alone for safety-critical decisions. See our disclaimer.