ClueLuma

Reactive power from real and apparent power calculator

Reactive demand magnitude is calculated as sqrt(S^2−P^2). Use the stated system boundary and matching input units.

Q=S2−P2Q = \sqrt{S^{2} - P^{2}}

Calculator

Enter the values you know and leave one box empty. Calculate finds the empty one, the result or any input.

kVA
kW
kVAR

Worked example

Given

  • SS = 500 kVA
  • PP = 400 kW
Q=5002−4002=300Q = \sqrt{{500}^{2} - {400}^{2}} = 300

Symbols and units

SymbolMeaningUnit
QQreactive demand magnitudekVAR
SSapparent powerkVA
PPreal powerkW

Related calculators

Results are estimates for study and screening. Check the inputs, units and assumptions before you use them for design, billing or contract decisions.