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Electrical

Reactive Power Calculator

Find reactive power magnitude from apparent power and power factor.

Ideal component relationshipsUnits and assumptions explained below
Circuit workbench
Circuit workbench

Keep RMS, peak and DC values distinct.

See the method

Enter circuit values

Runs on your device

Your circuit result

Your result

Let’s calculate.

Use the Calculate button to see your result.

Review the method below for assumptions and conventions.

How to use this tool

  1. Enter apparent power, power factor.
  2. Select Calculate to view the result.
  3. Check the method and assumptions below before using the result.

Input reference and sample values

Use the units and choices shown for each field. Sample values are provided for practice, not as recommendations.

InputFormat and unitsSample
Apparent powerNumeric value. Unit: VA. Must be greater than zero.1000
Power factorNumeric value. Zero or positive. Maximum: 1.0.8

Result for these sample inputs

600 var

Select Try the example in the form to load these values and calculate them again. This replaces the current form inputs. Compare the result with the method and worked explanation below.

The method, explained

Reactive power magnitude = apparent power × √(1 − power factor²).

A WORKED EXAMPLE

Using apparent power = 1000 VA, power factor = 0.8, the result is 600 var. Change these example inputs to match your task; use the method above to check each step.

What to keep in mind

Ideal-component calculation for study and estimation. It does not select safe wiring, protective devices or component ratings for an installation.

Methodology maintained by ClarityKit. How these tools are built and checked.