Amps to kW Calculator

Convert Amps to kW with the formula, a worked example and a table of typical values. Working shown step by step.

Line current 100 A, voltage 400 V, power factor 0.9, current type Three-phase AC gives

Real power: 62.354 kW · Output power: 57.366 kW

Estimate only. Not engineering or safety advice. Check the result against the applicable standard and the equipment data, and have a competent engineer review it before it is relied on. Terms of use.

Open in the calculator with these values

Formula

P = √3 × V × I × pf (three-phase L-N: 3 × V × I × pf; single-phase: V × I × pf; DC: V × I) Output = η × P

Worked example

Input	Value
Line current	100 A
Voltage	400 V
Power factor	0.9
Current type	Three-phase AC
Voltage type (three-phase only)	Line-to-line (L-L)
Efficiency	0.92

P = √3 × 400 × 100 × 0.9 = 62.3538 kW
Output = η × P = 0.92 × 62.3538 = 57.3655 kW

Typical values

Line current (A)	Real power (kW)	Output power (P × η) (kW)
5	3.118	2.868
10	6.235	5.737
20	12.471	11.473
50	31.177	28.683
100	62.354	57.366
200	124.708	114.731
500	311.769	286.828

Other inputs are the same as in the worked example above.

Assumptions

Balanced load
V is line-to-line RMS for three-phase unless line-to-neutral is chosen
DC takes the power factor as 1
Efficiency 1 means output power equals input power

Real power is electrical input power. Output (shaft) power is P × η and equals P when efficiency is 1.

Frequently asked questions

How do I convert Amps to kW?

P = √3 × V × I × pf (three-phase L-N: 3 × V × I × pf; single-phase: V × I × pf; DC: V × I); Output = η × P. Worked example: Line current 100 A, voltage 400 V, power factor 0.9, current type Three-phase AC gives Real power: 62.354 kW · Output power: 57.366 kW.

What do I need to enter?

Enter line current, voltage, power factor, current type, voltage type (three-phase only) and efficiency. Change the unit of a value with its selector and the result stays the same.

Does single-phase or three-phase change the answer?

Yes. Pick the circuit type that matches the supply. Three-phase uses √3 with the line-to-line voltage, single-phase uses the voltage as it is, and DC, where it is offered, takes the power factor as 1. The formula above shows each case.

Which power factor should I use?

Read it from the equipment nameplate or data sheet. Typical values are only a guide: about 1.0 for a resistive load and about 0.85 for a fully loaded induction motor. Do not use typical values for accurate work.

How accurate are the results?

Every figure comes from the same tested engine as the Elecmetric calculators and is meant for estimating. Check design values against the standard and the equipment data you work to.

Next steps in a design: Amps to kVA Three-Phase Power
Opposite direction: kW to Amps
Also see: HP to Amps Amps to HP Amps to kVA kVA to Amps
Formula guides: Three-Phase Power Formulas Power Factor and the Power Triangle AC Circuit Formulas: Reactance and Impedance
All 78 conversions Amps to kW in Elecmetric