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kW and amps, single or three phase.
Choose single-phase or three-phase, enter voltage and power factor, and convert kW to amps or amps to kW.
Short answer
Single phase: amps = kW x 1,000 / (volts x power factor). Balanced three phase: amps = kW x 1,000 / (1.732 x line-to-line volts x power factor). 10 kW at 480 V three phase and 0.8 power factor is 15.0 A; the same load on 240 V single phase is 52.1 A.
Inputs
Result
Worked example
A 20 A line current at 480 V three phase and 0.8 power factor is 1.732 x 480 x 20 x 0.8 = 13,300 W, or 13.3 kW (16.6 kVA). A 5 kW resistive heater on 240 V single phase (power factor 1) draws 5,000 / 240 = 20.8 A.
Formula, assumptions and sources
Single phase: P = V x I x PF. Balanced three phase: P = sqrt(3) x V(line-to-line) x I x PF, where sqrt(3) is about 1.732 and line-to-line voltage equals sqrt(3) times line-to-neutral voltage. Apparent power in kVA is kW divided by the power factor. Use a power factor of 1 for resistive loads like heaters; motors and drives are typically below 1, and the nameplate current is the reliable figure. Results assume balanced loads and sine-wave current. Not covered: unbalanced three-phase loads, motor starting current, and conductor or breaker sizing.
Table values here follow the NEC as reproduced in the sources below (editions 2008 to 2020 era); fill percentages, tables and allowances can change between editions, so confirm against the edition your jurisdiction has adopted.
Code and safety notes
This tool follows the U.S. National Electrical Code (NFPA 70). The Canadian Electrical Code (CSA C22.1) and local amendments differ in several tables and rules, so Canadian installations must be checked against the CEC and the authority having jurisdiction.
Planning aid only, not electrical advice. Electrical work can cause fire and shock; the adopted code edition, the equipment listing and a licensed electrician or inspector decide what is allowed.
FAQ
How do I convert kW to amps for three phase?
Amps = kW x 1,000 / (1.732 x line-to-line volts x power factor). For 15 kW at 208 V and a power factor of 0.9, that is 46.2 A.
What power factor should I use?
Use 1.0 for resistive loads such as heaters. For motors and electronics use the nameplate or a measured value; 0.8 is a common planning figure but it is an assumption.
Why is three-phase current lower for the same kW?
Three conductors share the load and the sqrt(3) factor applies, so the same kW draws about 58% of the single-phase current at the same line voltage.
Is kVA the same as kW?
No. kW is real power; kVA is apparent power. They match only when the power factor is 1.