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Conversion • kW • Amps

Convert kW to Amps

Convert power in kilowatts to current in amps – for single-phase or three-phase systems.

Calculation Values

Note: This calculator provides a technical estimate for guidance only. For electrical installations, standards, protective measures, installation method, ambient temperature, grouping, protective devices and manufacturer specifications must also be checked.

Formula Used

Single-phase: I = P / (U × cos φ)

Three-phase: I = P / (√3 × U × cos φ)

P is converted from kW to watts.

Frequently Asked Questions

Why is cos φ important?

For single- and three-phase systems, cos φ describes the power factor. It affects the current draw at the same real power.

What is the difference between kW and A?

kW describes power, amps describe current. The conversion depends on voltage and system type.

Which value should I use for cos φ?

For purely resistive loads, cos φ = 1 can be used. For many motors, approximately 0.8 to 0.9 is used.

Practical guidance

Convert kilowatts into realistic operating current

There is no fixed amperes-per-kW value: voltage, system type and power factor all change the result.

Input values explained

Power in kilowatts
Enter the electrical active power in kW. One kW equals 1,000 W; motor output power and electrical input power are not necessarily the same.
Voltage
Match the voltage to the selected electrical system. Single-phase calculations use line-to-neutral voltage, while three-phase calculations use voltage between two line conductors.
Power factor cos φ
cos φ is the ratio of active to apparent power. It is close to 1 for resistive heating loads; use the data-sheet value for motors and transformers.
Electrical system
Choose single-phase AC for a 230 V circuit and three-phase for a balanced three-phase system. This selection changes the formula factor.

Example: 11 kW three-phase

Use 11 kW electrical active power, 400 V and cos φ 0.90.

I = 11,000 W ÷ (√3 × 400 V × 0.90) ≈ 17.64 A

The result is about 17.64 A per line. The same power on 230 V single-phase would require much more current.

Identify input power correctly

A motor's kW marking may be mechanical output. Include efficiency or use nameplate current when that is the case.

Calculation limits

  • Efficiency, phase imbalance and inrush are not included automatically.
  • This conversion does not size a cable or protective device.