Skip to content
ENExplore Calculators

Reactive Power Calculator

Calculate reactive power and the correction needed to reduce it.

About Reactive Power Calculator

Reactive power circulates without doing work but still occupies supply capacity. Capacitors supply leading reactive power that cancels the lagging reactive power of motors, which is why correction is sized in kVAR. Correcting from 0.75 to 0.95 releases about a fifth of the apparent power, often deferring a transformer upgrade entirely.

Formula

Reactive Power

Q = P tan φ; correction = P (tan φ₁ − tan φ₂)

tan φ
Ratio of reactive to real power at a given power factor

Worked example

With the default values below, Reactive Power Calculator returns Present Reactive Power of 44.0959. Change any input above and every figure here is recalculated in your browser.

Inputs used

Real powerminimum 0 kW
50 kW
Present power factoraccepts 0.01–1
0.75
Target power factoraccepts 0.01–1
0.95

Results

Present Reactive Power
44.0959 kVAR
Reactive Power at the Target
16.4342 kVAR
Correction Capacitance Required
27.6616 kVAR
Present Apparent Power
66.6667 kVA
Apparent Power Released
14.0351 kVA

Step by step

  1. 1Values used
  2. 2Reactive Power
  3. 3Present Reactive Power= 44.0959 kVAR
  4. 4Reactive Power at the Target= 16.4342 kVAR
  5. 5Correction Capacitance Required= 27.6616 kVAR
  6. 6Present Apparent Power= 66.6667 kVA
  7. 7Apparent Power Released= 14.0351 kVA

Assumptions and limits

  • The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is Reactive Power calculated?

Q = P tan φ; correction = P (tan φ₁ − tan φ₂) Reactive power circulates without doing work but still occupies supply capacity. Capacitors supply leading reactive power that cancels the lagging reactive power of motors, which is why correction is sized in kVAR.

Why does Reactive Power matter?

Correcting from 0.75 to 0.95 releases about a fifth of the apparent power, often deferring a transformer upgrade entirely.

What values do I need to enter?

This calculator takes 3 inputs: Real power, Present power factor, Target power factor. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.

Related Calculators

Reactive Power Calculator – Calculate Present Reactive Power