Free Tool

Power Factor Correction Calculator

Calculate the required capacitor bank size in kilovars (kVAr) to raise the power factor from its current value to a target value — with the formula shown and the apparent power capacity freed up.

Approximate Required Capacitor Size

This result is approximate for initial engineering guidance. Selecting the actual bank should account for standard available ratings, staged switching, harmonics, and network conditions — consult a detailed study before implementation.

Equation Used

Q (kVAr) = P (kW) × [tan φ₁ − tan φ₂]

Where φ₁ is the angle of the current power factor and φ₂ is the angle of the target power factor. The bracketed term is the "multiplier" that well-known practical tables condense into a single value.

Worked Example

A 400 kW load with a power factor of 0.8 that we want to improve to 0.95 — multiplier ≈ 0.421:

Q = 400 × 0.421 ≈ 168.4 kVAr

The apparent power drops from 500 kVA to about 421 kVA — freeing up ~79 kVA of capacity on the supply transformer.

Want to understand substations step by step?

Follow trainer Fahad Refai's Substations and Electrical Maintenance courses — a practical walkthrough from maintenance fundamentals to SCADA systems.

Browse Fahad Refai's Courses