Power factor calculator

Calculate power factor as real power in watts divided by apparent power in volt-amperes.

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Real power (W)

Apparent power (VA)

Answer

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Calculate power factor as real power in watts divided by apparent power in volt-amperes.

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Precision and calculation record

Decimal places in numeric results and text downloads

Rounding changes displayed numbers, not the calculation. Text, fractions, matrices and CSV schedules keep their own formatting. Automatic keeps up to 12 significant digits, with money shown to cents where applicable.

Saved scenario

Save the current answer, then change an input to compare. This clears when you leave.

Formula and assumptions

This ratio includes distortion and displacement effects in the supplied measured powers. It cannot identify leading/lagging behavior or a phase angle without further waveform assumptions.

Automatic precision shows numbers to 12 significant digits. Thousands separators such as 1,000 are accepted; use a dot for decimals.

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Updated 2026-09-26

Using Power factor calculator

Calculate power factor as real power in watts divided by apparent power in volt-amperes.

This ratio includes distortion and displacement effects in the supplied measured powers. It cannot identify leading/lagging behavior or a phase angle without further waveform assumptions.

Next: Electricity cost calculator

A worked example

Example inputs: real power (w) = 800, apparent power (va) = 1000. Power factor = 0.8.

Before you use the result

This ratio includes distortion and displacement effects in the supplied measured powers. It cannot identify leading/lagging behavior or a phase angle without further waveform assumptions.

Example results for real power (w)

These examples use Apparent power (VA): 1000. They are reference calculations, not recommended settings.

Real power (W)	Power factor
400	0.4
800	0.8

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