Three-Phase Power Calculator

Estimate balanced three-phase apparent, real, and useful output power from line voltage and line current.

Line-to-line RMS voltageNumber from 0.001 to 1000000 V.Line currentNumber from 0 to 1000000 A.Power factorNumber from 0 to 1.EfficiencyNumber from 0.1 to 100 %.

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

Apparent power41.56921938 kVA

Real input power35.33383647 kW

Useful output power33.21380629 kW

Apparent power41569.21938 VA

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

For a balanced system using line-to-line voltage, S = √3 × V × I. Real power = S × power factor; output applies efficiency.

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

Line-to-line RMS voltage = 480 V; Line current = 50 A; Power factor = 0.85; Efficiency = 94 %. The calculator returns Apparent power = 41.56921938 kVA; Real input power = 35.33383647 kW; Useful output power = 33.21380629 kW; Apparent power = 41569.21938 VA.

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

Limitations and safety

Do not apply this formula to an unbalanced system without phase-by-phase analysis. Wiring configuration, harmonics, motor starting and electrical codes require qualified design.

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

Why does the formula use square root of three?

It comes from the 120-degree phase relationship between the three balanced phase quantities when line values are used.

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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