Enter your line-to-line voltage (V), current (A), and power factor to calculate three-phase power. The calculator returns active power (kW), apparent power (kVA), and reactive power (kVAR) for any three-phase AC system.
Active Power
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Apparent Power
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Reactive Power
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Active Power (W)
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Apparent Power (VA)
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Three-phase active power (kW) is calculated using the formula: P = (√3 × V_LL × I × cosΦ) / 1000, where V_LL is the line-to-line voltage in volts, I is the current in amperes, and cosΦ is the power factor. The √3 factor (approximately 1.7321) accounts for the three-phase system geometry.
Active power (kW) is the real power actually consumed and converted to useful work, such as heat or mechanical energy. Apparent power (kVA) is the total power supplied by the source, combining both active and reactive components. The ratio between them is the power factor: PF = kW / kVA.
Reactive power (kVAR) is the power stored and released by inductive or capacitive elements in the circuit — it does no useful work but is necessary to maintain the magnetic and electric fields in motors and transformers. It is calculated as Q = (√3 × V_LL × I × sinΦ) / 1000, where sinΦ = √(1 − cosΦ²).
The power factor (cosΦ) represents the efficiency of power usage in an AC circuit, ranging from 0 to 1. A value of 1 means all supplied power is used as active power. Typical values include: resistive heaters (1.0), induction motors at full load (0.85–0.90), motors at partial load (0.70–0.80), and fluorescent lighting with ballast (0.50–0.70).
This calculator uses the line-to-line (phase-to-phase) voltage, also written as V_LL. For common supply systems, use 415 V for 400 V European systems, 480 V for North American industrial systems, or 208 V for North American commercial three-phase systems. If you only have the line-to-neutral voltage, multiply it by √3 (≈ 1.732) to get the line-to-line value.
To find current (amps) from known power, rearrange the formula: I = (P_kW × 1000) / (√3 × V_LL × PF). For example, a 10 kW load on a 415 V supply with a 0.85 power factor draws approximately I = 10,000 / (1.732 × 415 × 0.85) ≈ 16.4 A.
In a balanced three-phase system, the three phases are 120° apart. When you use line-to-line voltage instead of phase voltage, a factor of √3 (≈ 1.7321) naturally arises from the vector relationships between the phases. It scales the single-phase power formula up to account for all three phases simultaneously.
Yes. As long as you enter the line-to-line voltage and line current, the formulas apply equally to both star (wye) and delta connected three-phase loads. The relationship between phase and line quantities differs internally between the two configurations, but the total three-phase power calculations using line values are identical.