Commercial AC formula
kW and Amps Calculator
Convert kW to amps or amps to kW for larger AC loads using voltage, phase, and power factor.
Convert kW and Amps
Convert commercial and industrial AC load values between kW and amps; for example, 15 kW at 480 V three-phase and PF 0.90 draws 20.1 A.
Result
Amps
20.05 A
Result notes
Keep the entered values, assumptions, and result together when adding this calculation to job notes or submittal records. Final installation choices should align with the applicable code edition, equipment listing, manufacturer instructions, local amendments, and AHJ requirements.
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Formula and field context
Convert kW to amps or amps to kW for larger AC loads using voltage, phase, and power factor.
Formula context
Single Phase vs Three Phase Chart
Single-phase and three-phase are not just different voltages; they are different calculation contexts. Single-phase formulas use one voltage and one current path. Balanced three-phase formulas use line-to-line voltage, line current, and the 1.732 multiplier. Split-phase 120/240 V services can have both 120 V line-to-neutral loads and 240 V line-to-line loads on the same service.
Formula
Single phase: P = V x I x PF. Balanced three phase: P = 1.732 x VLL x I x PF.Variables to keep with the result
- P is real power in watts.
- V is the voltage across the single-phase load.
- VLL is line-to-line voltage for balanced three-phase loads.
- I is line current.
- PF is power factor.
Formula and variables
For single-phase AC, amps equals kW times 1,000 divided by volts and power factor. For balanced three-phase AC, amps equals kW times 1,000 divided by the square root of 3, line-to-line voltage, and power factor. Keep the voltage basis, phase, and power factor with every result because each one changes the current.
U.S. field example
A 15 kW balanced three-phase load at 480 V and 0.90 power factor draws about 20.1 A. The same kW on a lower-voltage system draws more current. This is why commercial load notes must keep kW, voltage, phase, and PF together instead of copying a current value without context.
When to use the full calculator
This worksheet covers the kW and current relationship. The full power calculator adds apparent power or reactive power, while wire, breaker, motor, transformer, and voltage-drop calculators handle sizing or code decisions tied to the current result.