Power Factor Correction Calculator
Motors and many commercial loads draw reactive power as well as real power, and that lowers the power factor. This shows how many kilovars of capacitor correction a load needs to reach a higher power factor.
- Free
- Works offline after your first visit
- Saves on this device
- No sign-up
- Updated
How it works
Find the angle whose cosine is the power factor, take its tangent, and multiply by the real power in kilowatts. Do this for the power factor you have now and for the one you want.
The capacitor size is the reactive power now minus the reactive power at the target. If the target is not higher than today, the answer is zero.
Worked example
A 50 kW load running at a power factor of 0.75 needs about 27.7 kvar of capacitors to reach 0.95. Today it carries 44.1 kvar of reactive power, and at 0.95 it would carry 16.4 kvar.
Questions
Why does power factor matter?
A low power factor means the wiring carries more current than the real work needs. Some utilities add a charge for a low power factor, so correcting it can save money as well as current.
Is the answer the capacitor size I should buy?
It is the size the math calls for. Capacitor banks come in standard sizes, and a qualified electrician or engineer should check the final choice, the voltage and any motor starting issues.
What power factor should I aim for?
Many utilities look for something near 0.95 or higher, but the right target depends on your utility's rules and your equipment.
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