Power Factor Calculator

Calculate power factor, reactive power, and phase angle from real power and apparent power.

Real powerNumber from 0 to 1000000 kW.Apparent powerNumber from 0.000001 to 1000000 kVA.

Use the units shown beside each field. Decimal and scientific notation are accepted for non-integer fields; blanks, commas, fractions and non-finite entries are rejected.

Calculate

Power factor0.8

Reactive power6 kVAR

Phase angle36.86989765°

Real-power share80%

The displayed results apply to the default example. Enable JavaScript to calculate other inputs.

How to use this calculator

1. Replace the example values with measurements or ratings for the exact vehicle, circuit, component or system.
2. Keep every value in the labeled unit and use manufacturer data where available.
3. Select Calculate, then review the result together with the limitations and safety notes.

Formula and method

Power factor = kW ÷ kVA. Reactive power = √(kVA² − kW²). Phase angle = arccos(power factor).

Calculations run in your browser. Results are hidden whenever an input changes or validation fails, preventing an older result from being mistaken for a new calculation.

Worked example

Real power = 8 kW; Apparent power = 10 kVA. The calculator returns Power factor = 0.8; Reactive power = 6 kVAR; Phase angle = 36.86989765°; Real-power share = 80%.

The worked example uses the same defaults shown in the interface, allowing the formula and displayed result to be checked together.

Limitations and safety

This magnitude-only model does not identify leading versus lagging power factor and assumes sinusoidal quantities. Harmonics require additional analysis.

This is an educational planning model. Confirm ratings, tolerances, code requirements and safe procedures with manufacturers and qualified professionals before purchasing, modifying, wiring or operating equipment.

Frequently asked questions

Can power factor be greater than one?

No. In this model real power cannot exceed apparent power, so inputs producing a value above one are rejected.

Why does the calculator reject my entry?

Each field shows its supported range. Whole-number fields reject decimals, and all fields reject blanks, words, comma-formatted numbers, fractions and non-finite values.

How should I use the displayed precision?

Keep extra digits while checking the calculation, then round to the precision supported by the measurements, component tolerances and published ratings.

Review notes and reference

Reviewed October 4, 2026. The formula and default example were checked together. The script was tested for defaults, input boundaries, invalid formats, condition-specific errors and recovery after an error. Reference: OSHA electrical safe-work requirements. Explanations and examples are original.

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