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Power Factor Calculator

Online calculator tool to assess power factor of a consumer. As default real power (kW) is fixed, either reactive power or apparent power could be fixed, calculator will estimate the other power and power factor.




Power Factor

How to calculate power factor

The power factor of an AC load or consumer is the ratio between the true power P (kW) and the apparent power S (kVA). At the same time, the power factor angle equals phase angle between the voltage across the circuit (or load) and the current through the circuit (or load).

Inductive loads have a lagging power factor, capacitive loads have a leading power factor. The majority of industrial loads, such as motors and air conditioners, are inductive (lagging power factor). Thus, engineers often refer to capacitors or capacitive loads as sources of reactive power.

Power factor improvement in plant

Power-factor improvements provide benefits to plant operation:

  • Prevent penalty from utility low power factor
  • Less voltage drop
  • Reduce power system loss

Formula for capacitor rating required to improve the power factor is:


  • kVAR : Reactive power
  • kW : Real power
  • Φ1 : Origin power factor
  • Φ2 : Improved power factor

A tables that give kW multiplier for determining the reactive power requirements could be referred to table 8-2 of IEEE Std 141 Recommended Practice for Electric Power Distribution for Industrial Plants.