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Three-Phase Power Calculator

Enter RMS line-to-line voltage, RMS line current and a displacement power factor from 0 to 1. Results are total electrical power across three phases for a balanced, sinusoidal, lagging load.

Local calculation · inputs stay in your browser

Inputs

Results

    An input link contains the values you entered. Share only information you want to disclose.

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    Formula and method

    S = √3 × Uline × Iline / 1000; P = S × PF; Q = S × √(1 − PF²); φ = arccos(PF). Use V and A for results in kVA, kW and kvar.

    Worked example

    400 V, 10 A, PF 0.85: S ≈ 6.928 kVA, P ≈ 5.889 kW, Q ≈ 3.650 kvar.

    Assumptions and limits

    • For a 400 V system, enter 400 V between phases, rather than approximately 230 V to neutral. Results already include all three phases.
    • Motor electrical input differs from shaft output: shaft output equals active electrical input multiplied by motor efficiency. This calculator does not estimate shaft power.
    • VFDs, rectifiers, significant harmonics and unbalanced loads require suitable phase-by-phase measurements; this cos φ model does not replace true-power analysis.

    Frequently asked questions

    Why does the formula use √3?

    Balanced three-phase power is three times per-phase power. Expressing it with line-to-line voltage gives the √3 factor.

    What happens at a power factor of 1?

    In the sinusoidal model, φ is 0°, reactive power is zero and active power equals apparent power numerically.

    References

    Three-Phase Power Calculator practical guide and common questions

    What does Three-Phase Power Calculator calculate?

    Enter RMS line-to-line voltage, RMS line current and a displacement power factor from 0 to 1. Results are total electrical power across three phases for a balanced, sinusoidal, lagging load. S = √3 × Uline × Iline / 1000; P = S × PF; Q = S × √(1 − PF²); φ = arccos(PF). Use V and A for results in kVA, kW and kvar.

    When is this useful?

    400 V, 10 A, PF 0.85: S ≈ 6.928 kVA, P ≈ 5.889 kW, Q ≈ 3.650 kvar.

    How do I enter the inputs?

    Enter the inputs for Three-Phase Power Calculator: Line voltage (line-to-line RMS), Line current (RMS), Displacement power factor cos φ. Calculate, check the units and assumptions, then copy or download the results.

    How should I interpret the results?

    For a 400 V system, enter 400 V between phases, rather than approximately 230 V to neutral. Results already include all three phases. Motor electrical input differs from shaft output: shaft output equals active electrical input multiplied by motor efficiency. This calculator does not estimate shaft power. VFDs, rectifiers, significant harmonics and unbalanced loads require suitable phase-by-phase measurements; this cos φ model does not replace true-power analysis.

    Where are my inputs processed?

    Three-Phase Power Calculator runs in this browser. Inputs are not uploaded to a calculation server; copying and CSV download require your action. The existing site analytics and advertising still load.