Power Factor Correction Calculator

About this calculator

This calculator finds the reactive power a correction capacitor must supply, Qc = P·(tanφ₁ − tanφ₂), to raise a system's power factor from its current value (cosφ₁) to a target value (cosφ₂), where P is real power and the tangent terms come from the phase angle between voltage and current in each state. Poor power factor (common in industrial loads with many motors) means more current is drawn than the real power actually used requires, since some current only supports the reactive (non-working) component of the load.

Electrical engineers and plant maintenance staff sizing capacitor banks to avoid utility power-factor penalty charges, and electrical engineering students studying AC power systems use this. Enter the load's real power and its current and target power factors to get the required capacitor reactive power.