3 Phase Current Calculator

Q: What is the three phase current formula?

I = (kW × 1000) ÷ (√3 × V × PF). Where √3 ≈ 1.732 and V is the line-to-line voltage.

Q: What is the difference between line voltage and phase voltage in three phase?

Line voltage is the voltage between any two phases. Phase voltage is the voltage from one phase to neutral. For a 415V line voltage system, phase voltage = 415 ÷ √3 = 240V.

Q: Why does three phase draw less current than single phase for the same power?

Three phase distributes power across three conductors, so each carries only 1/√3 of the current compared to a single phase system at the same power and voltage. This reduces conductor losses and allows smaller wiring.

Calculate three phase line current from power (kW), line voltage, and power factor. Works for 415V, 400V, 480V, and all standard three phase systems.

This calculator provides estimates only. Always consult a qualified electrician for real installations.

Calculate Three Phase Current

Power (kW)

Line Voltage (V)

Power Factor

Result

—

Line Current (Amps)

—

Apparent Power (kVA)

Formula

I = (kW × 1000) ÷ (√3 × V_line × Power Factor)

Where √3 ≈ 1.732. Use the line-to-line voltage (e.g. 415V, 400V, 480V) — not the phase-to-neutral voltage.

Example Calculations

UK/Australia (415V): A 22 kW motor at PF = 0.88.

I = (22 × 1000) ÷ (1.732 × 415 × 0.88) = 22,000 ÷ 632.9 = 34.76 A

US Industrial (480V): A 30 kW motor at PF = 0.90.

I = (30 × 1000) ÷ (1.732 × 480 × 0.90) = 30,000 ÷ 747.6 = 40.13 A

Common Three Phase Voltages

415V (UK/AUS/IND): Standard three phase in UK, Australia, India — 240V phase to neutral.
400V (EU): European standard — 230V phase to neutral.
480V (US industrial): Common for US industrial motors and equipment.
208V (US commercial): US 120/208V wye systems.
440V (legacy): Older installations — check equipment nameplates.

Frequently Asked Questions

What is the three phase current formula?

I = (kW × 1000) ÷ (√3 × V × PF), where √3 ≈ 1.732 and V is the line-to-line voltage. For 415V, three phase, PF=0.85, and 10kW: I = 10000 ÷ (1.732 × 415 × 0.85) = 16.39A.

What is the difference between line voltage and phase voltage?

Line voltage is measured between two phases (e.g. 415V). Phase voltage is from phase to neutral (e.g. 240V). Line = Phase × √3. Always use line voltage in the three phase current formula.

Why does three phase draw less current than single phase for the same power?

Power is shared across three phases. Each phase carries 1/√3 (≈57.7%) of the current compared to a single phase circuit at the same power and phase voltage. This makes three phase more efficient for large loads.