kW to Amps Calculator - DC, Single-Phase and Three-Phase

Agarapu Ramesh — Editor and content reviewer
Editorially reviewed Reviewed by Agarapu Ramesh, science educator (chemistry). LinkedIn
Last reviewed: May 2026 | Standard electrical engineering formulas

kW tells you real power. Amps tell you current. To convert kW to amps you need voltage, and in AC you need power factor. Three-phase current is lower for the same kW because the load is shared across three lines.

Formula at a glance

  • DC: A = kW x 1000 / V
  • single-phase: A = kW x 1000 / (V x PF)
  • three-phase: A = kW x 1000 / (1.732 x V x PF)

Field note: Do not use this result alone to choose cable. Apply code rules, derating and voltage drop. The formula gives current, not permission.

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Calculator Tool

Convert kilowatts to amperes

kW
V
Result
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Formulas

DCI = (kW×1000) ÷ V
AC 1-PhaseI = (kW×1000) ÷ (V×PF)
AC 3-PhaseI = (kW×1000) ÷ (√3×V×PF)

Quick Reference

kW @240V @480V
1 kW 4.17A 2.08A
5 kW 20.83A 10.42A
10 kW 41.67A 20.83A
50 kW 208.3A 104.2A

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How to use the kW to Amps Calculator

Use this as a fast electrical check, then compare the result with the nameplate, measured voltage and power factor. The formula is clean. Real panels, motors and UPS loads usually have one extra wrinkle.

Worked example

Example: 5 kW at 240 V single-phase and PF 1 draws 20.83 A. At PF 0.85 it draws 24.51 A.

Practical checks before you trust the number

  • For motors, starting current is much higher than calculated running current.
  • For heaters, PF is usually close to 1.
  • For three-phase, use line-to-line voltage such as 400 V, 415 V or 480 V.

Common mistake

Do not use this result alone to choose cable. Apply code rules, derating and voltage drop. The formula gives current, not permission.

Sources and references

Related calculators

Frequently Asked Questions

Convert kW to W (×1000) then divide by V × PF (or √3 × V × PF for three-phase). Single-phase: A = (kW × 1000) ÷ (V × PF). Three-phase: A = (kW × 1000) ÷ (√3 × V × PF). Example: 5 kW on 230 V single-phase, PF 0.9 → A = 5000 ÷ (230 × 0.9) = 24.2 A. This sizes cable and breaker on every residential subpanel feeder we install.

DC: A = (kW × 1000) ÷ V. No PF, no √3. Example: 2 kW DC load on a 48 V battery bank → A = 2000 ÷ 48 = 41.7 A. That's a big DC current, so you need a short, fat copper run or a fuse rated 50 A nearby. DC currents at low voltage drive cable size more than anything else, especially in solar and EV systems.

A = (kW × 1000) ÷ (V × PF). Example: 3 kW at 230 V single-phase, PF 0.85 → A = 3000 ÷ (230 × 0.85) = 15.3 A. For a 16 A circuit you're at the edge — go up to 20 A breaker and 2.5 mm² copper minimum. For PF 1 (heaters), the same kW gives only 13 A, so you have more headroom on resistive loads.

Three-phase: A = (kW × 1000) ÷ (√3 × V_line × PF). Example: 10 kW at 415 V, PF 0.85 → A = 10000 ÷ (1.732 × 415 × 0.85) = 16.4 A per phase. For motor protection, this is the running current; starting current can be 6 to 8 times that. Set the overload at 110–125% of the running current, and use a properly rated contactor.

Use the actual PF. Resistive heaters: PF = 1. LED panels and modern electronics: 0.9 to 0.95. Old single-phase motors: 0.6 to 0.75. Three-phase induction motors at full load: 0.8 to 0.9. At part-load, PF drops sharply, so the running current can be higher than expected. For mixed loads on a panel, use a weighted average PF — typically 0.85 to 0.9 for residential.

Single-phase, PF 1: A = (5 × 1000) ÷ 240 = 20.8 A. Single-phase, PF 0.85: A = 5000 ÷ (240 × 0.85) = 24.5 A. So pick a 25 A or 32 A breaker depending on PF. For a 5 kW geyser (resistive), 20 A is enough. For a 5 kW motor or compressor, you'll need 32 A and 4 mm² cable. Always confirm PF before final selection.

Yes, this is exactly its job. The calculator gives you running current, then you apply the 125% continuous load factor and select cable and breaker. Example: 24 A calculated × 1.25 = 30 A → use 4 mm² copper rated for 32 A, with a 32 A MCB. Always derate cable for ambient temperature, conduit fill, and bunching — those derating factors are not in basic calculators.