Engineering

3 Phase Current Calculator

Calculate three-phase current from kW or kVA, or convert amps back to kW and kVA. This calculator targets the practical search intent around 3 phase amps, 400 V three-phase current, 415 V current, and 480 V three-phase loads.

3-phase-current
Three-phase current
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Apparent power—
Formula used—

Three-phase current formulas

This page focuses only on three-phase current. It is useful when the search intent is specifically for 3 phase amps, 3 phase kW to amps, 3 phase kVA to amps, or current at voltages such as 208 V, 400 V, 415 V, and 480 V.

Using line-to-line voltage: Amps = kW × 1000 ÷ (√3 × V × PF) Amps = kVA × 1000 ÷ (√3 × V) Using line-to-neutral voltage: Amps = kW × 1000 ÷ (3 × V × PF) Amps = kVA × 1000 ÷ (3 × V)

Worked example: 20 kW at 400 V three-phase

Given: Real power = 20 kW Voltage = 400 V line-to-line Power factor = 0.8 Amps = 20 × 1000 ÷ (√3 × 400 × 0.8) Amps = 36.08 A

The same 20 kW load would draw a different current at 208 V, 415 V, or 480 V because voltage changes the current required for the same power.

Common three-phase current table at PF 0.8

kW208 V400 V415 V480 V
5 kW17.35 A9.02 A8.70 A7.52 A
10 kW34.69 A18.04 A17.39 A15.04 A
20 kW69.39 A36.08 A34.78 A30.07 A
50 kW173.47 A90.21 A86.96 A75.18 A

Line-to-line vs line-to-neutral voltage

Most three-phase formulas online use line-to-line voltage. That is usually the voltage printed on three-phase equipment nameplates and supply descriptions, such as 400 V, 415 V, or 480 V. Line-to-neutral voltage is lower and is used when measuring between one phase and neutral. The calculator supports both so the result matches the voltage you actually enter.

Common questions

  • It calculates current, real power, or apparent power for a balanced three-phase AC system using voltage, power factor, and either kW, kVA, or amps.
  • Using line-to-line voltage, A = kW × 1000 ÷ (√3 × V × PF).
  • Using line-to-line voltage, A = kVA × 1000 ÷ (√3 × V).
  • At 400 V three-phase and 0.8 power factor, 20 kW is about 36.08 amps.
  • At 415 V three-phase and 0.8 power factor, 10 kW is about 17.39 amps.
  • Yes for kW-to-amps calculations. Lower power factor increases the current needed for the same real kW load.
  • No. kVA is apparent power, so kVA-to-amps does not need power factor. Power factor is needed to convert between kW and kVA.
  • Use the voltage type that matches your measurement or nameplate. Most three-phase supply ratings such as 400 V, 415 V, and 480 V are line-to-line.
  • The √3 factor appears when calculating balanced three-phase power from line-to-line voltage because the three phase voltages are separated by 120 degrees.
  • It is intended for balanced three-phase estimates. Unbalanced systems require phase-by-phase measurement or calculation.