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AC power calculator (kW, kVA, kVAR)

Real, apparent and reactive power from voltage, current and power factor.

V
A

Calculating…

How it's calculated

Three-phase: S = √3 × V × I Single-phase: S = V × I P = S × PF Q = √(S² − P²)

Real power (kW) does the work. Apparent power (kVA) is what cables, transformers and generators have to carry. Reactive power (kVAR) is the difference, drawn by motors and other inductive loads.

Use line-to-line voltage for three-phase supplies: 400 V in the UK and EU, 480 V or 208 V in the US.