Power Factor Calculator
Calculate the power factor of an AC electrical system from real power and apparent power (or reactive power).
What is power factor?
Power factor (PF) measures how effectively an AC electrical circuit converts supplied power into useful work. It is the ratio of real power (kW), which does actual work, to apparent power (kVA), which is what the supply must deliver. A power factor of 1.0 (unity) means all supplied power is used effectively; lower values mean more current is needed to deliver the same real power.
How this calculator works
Choose whether you know apparent power (kVA) or reactive power (kVAR) alongside real power (kW). The calculator uses the power triangle relationship kVA² = kW² + kVAR² to find the missing value, then computes power factor as PF = kW ÷ kVA and the corresponding phase angle as the arccosine of PF.
This tool is for general educational and planning purposes. For circuit design, protection sizing, or utility power-factor penalty calculations, consult a qualified electrical engineer.