Single-phase AC
I = 1000 × P ÷ (V × PF)
P = V × I × PF ÷ 1000
kW to Amps Calculator
Convert kilowatts to amps, or amps to kilowatts, for single-phase AC, balanced three-phase AC and DC. Enter your supply voltage and power factor to see the formula and calculation.
Use active electrical power, not kVA or motor shaft power.
Use voltage between phases, e.g. 400 V, not 230 V to neutral.
0.85 is an example, not a universal motor value. Use the measured or specified PF at your operating load.
Try an example:
Calculated line current
A
I = 1000 × P ÷ (√3 × V × PF)
Complete the inputs to see your calculation.
Approximate steady-state result. Not a cable, breaker or motor-starting rating.
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How do you convert kW to amps?
For single-phase AC, amps = kW × 1000 ÷ (volts × power factor). For balanced three-phase AC, amps = kW × 1000 ÷ (√3 × line-to-line volts × power factor). For DC, amps = kW × 1000 ÷ volts. There is no fixed conversion from kW to amps: the voltage and electrical system matter.
Balanced three-phase AC
I = 1000 × P ÷ (√3 × V × PF)
P = √3 × V × I × PF ÷ 1000
DC
I = 1000 × P ÷ V
P = V × I ÷ 1000
P = active electrical input power in kW; I = current in A (line current for three-phase); V = volts (RMS for AC, line-to-line for three-phase); PF = power factor, greater than 0 and no more than 1. Three-phase calculations assume balanced loads and a sinusoidal supply voltage. Use true power factor if current harmonics are present; cos φ alone may not represent it.
Worked examples and conversion table
10 kW at 400 V three-phase, PF 0.85: I = 10,000 ÷ (√3 × 400 × 0.85) ≈ 16.98 A. This is line current with 10 kW of electrical input power.
5 kW at 230 V single-phase, PF 1: I = 5,000 ÷ 230 ≈ 21.74 A. 1.2 kW at 24 V DC: I = 1,200 ÷ 24 = 50 A.
| Input power | 230 V single-phase PF 1 | 400 V three-phase PF 0.85 |
|---|---|---|
| 1 kW | 4.35 A | 1.70 A |
| 5 kW | 21.74 A | 8.49 A |
| 10 kW | 43.48 A | 16.98 A |
| 15 kW | 65.22 A | 25.47 A |
Common kW and amps questions
Can I enter the kW rating from a motor nameplate?
Check whether the rating is mechanical shaft output. This calculator requires electrical input power. If shaft power is 10 kW and efficiency is 90%, input power is 10 ÷ 0.90 ≈ 11.11 kW. At 400 V three-phase and PF 0.85, that gives approximately 18.87 A. Use the motor full-load current calculator when working from shaft power and efficiency. The manufacturer's rated current takes precedence over an estimate.
Should I enter 230 V or 400 V for a three-phase supply?
Enter the line-to-line voltage. On a 230/400 V system, this is 400 V. The √3 formula uses line-to-line voltage and line current. It does not calculate individual currents for an unbalanced three-phase load.
Why does a lower power factor increase the current?
At the same active power and voltage, current is inversely proportional to power factor. A 10 kW, 400 V three-phase load needs about 14.43 A at PF 1 and 18.04 A at PF 0.80. kW is active power; kVA is apparent power. They are equal only when PF is 1.
Can this result size a breaker, cable or soft starter?
Use this result as a steady-state estimate. Selection also depends on the manufacturer's specifications, starting current, duty, ambient conditions, installation method and applicable electrical requirements. For a motor or VFD, check the specific rated input and output currents before selecting components.
How do I convert amps back to kW?
Select “Amps → kW” above. For single-phase AC, multiply volts × amps × PF and divide by 1000. For balanced three-phase AC, also multiply by √3 using line-to-line voltage. For DC, multiply volts × amps and divide by 1000.
Calculation basis and sources
The AC equations and the distinction between shaft power and electrical input power follow Schneider Electric's Electrical Installation Guide: definition of reactive power. The calculator rearranges the active-power equations and converts kilowatts to watts using 1 kW = 1000 W.
For the relationship between active power, apparent power and PF, see the guide's definition of power factor.
The calculated examples are provided by KOEED. They are illustrative operating points, not manufacturer ratings or a component recommendation. Formula and example review: .