kW to Amps Calculator

Find the current in amps for any load in kilowatts, on single phase or 3 phase supplies. Enter the kW, phase, voltage and power factor. The current updates instantly.

Single phase: I = (kW × 1000) ÷ (V × PF)

3 phase: I = (kW × 1000) ÷ (√3 × V × PF)

Where: I = current in amps (per phase for 3 phase) · kW = real power · V = voltage (line-to-line for 3 phase) · PF = power factor · √3 ≈ 1.732

Example: 100 kW, 3 phase 400V, PF 0.8: 100000 ÷ (1.732 × 400 × 0.8) = 180.4A per phase

Convert kW to Amps

⇄ Switch to Amps to kW

Real power

Phase

Single phase3 phase

Voltage

UK mains: 230V single phase, 400V 3 phase (line-to-line). 110V is used for site tools.

Power factor

Diesel generators are rated at 0.8 PF. Use 1.0 for purely resistive loads such as heaters.

Current

180.4A per phase

100000 ÷ (1.732 × 400V × 0.8) = 180.4A

Browse generators around 100 kW: 100 kW Generators

Generators closest to 100 kW

Grupel PL110D5

Cummins C110D5Q

Cummins C110D5

Cummins C150D5

kW to amps conversion table: single phase

Voltage

Power factor

kW to amps, single phase 230V, PF 0.8
kW	Amps
1 kW	5.4
2 kW	10.9
3 kW	16.3
5 kW	27.2
7.5 kW	40.8
10 kW	54.3
12 kW	65.2
15 kW	81.5
16 kW	87.0
20 kW	108.7
25 kW	135.9
30 kW	163.0
40 kW	217.4
50 kW	271.7

kW to amps conversion table: 3 phase (per phase)

Voltage

Power factor

kW to amps, 3 phase 400V, PF 0.8
kW	Amps per phase
5 kW	9.0
10 kW	18.0
15 kW	27.1
20 kW	36.1
25 kW	45.1
30 kW	54.1
40 kW	72.2
50 kW	90.2
70 kW	126.3
80 kW	144.3
100 kW	180.4
150 kW	270.6
200 kW	360.8
250 kW	451.1
300 kW	541.3
400 kW	721.7
500 kW	902.1
600 kW	1082.5
700 kW	1263.0
800 kW	1443.4
900 kW	1623.8
1000 kW	1804.2
1500 kW	2706.3
2000 kW	3608.4

How many amps in a kW?

It depends on the voltage, the number of phases and the power factor. Here's how many amps 1 kW draws on common UK supplies:

Supply	PF 1.0 (resistive)	PF 0.8 (typical generator load)
Single phase 230V	4.35A	5.43A
Single phase 110V (site tools)	9.09A	11.36A
3 phase 400V (per phase)	1.44A	1.80A

To find the amps for a bigger load, multiply these figures by the kW. Or use the calculator above, which does the conversion for any voltage and power factor.

The kW to amps formula explained

Single phase: amps = kW × 1000 ÷ (volts × power factor)
3 phase: amps = kW × 1000 ÷ (1.732 × volts × power factor)

Multiplying by 1000 converts kilowatts to watts. Dividing by the voltage gives the current. The power factor is there because a load with a PF below 1 draws more current than its kW alone suggests. On 3 phase, the 1.732 (√3) accounts for the power being shared across three phases. The answer is the current in each phase.

Worked examples

Load	Supply	Calculation	Amps
3 kW heater	Single phase 230V, PF 1.0	3000 ÷ 230	13.0A
10 kW	Single phase 230V, PF 0.8	10000 ÷ (230 × 0.8)	54.3A
100 kW	3 phase 400V, PF 0.8	100000 ÷ (1.732 × 400 × 0.8)	180.4A per phase
400 kW	3 phase 400V, PF 0.8	400000 ÷ (1.732 × 400 × 0.8)	721.7A per phase

The first row is why a standard 13A plug tops out at around 3 kW.

kW to amps on a 3 phase supply

Most generators above small domestic sizes are 3 phase. When you convert kW to amps for 3 phase, the result is the current per phase, the figure you compare with breaker, cable and switchgear ratings. For example, a 100 kW generator at 400V and 0.8 PF delivers about 180A per phase, and a 400 kW generator about 722A per phase. Browse all 3 phase generators.

Using kW to amps when specifying a generator

Protection and cabling: the generator's output breaker and cables are sized from its full-load current.
Transfer switching: ATS panels and manual changeover switches are rated in amps. Choose a rating at or above the generator's full-load current, e.g. a 100 kW / 400V set at 180A per phase would typically pair with a 200A switch.
Motor starting: a motor can draw several times its running current while it starts. If you're powering pumps, compressors or other motor loads, size the generator for the starting current, not just the running current.
Single phase loads on a 3 phase generator: spread them evenly across the three phases, so no single phase is overloaded.

kW to Amps FAQs

How many amps is 1 kW?

On a single phase 230V supply, 1 kW draws 4.35A at unity power factor, or 5.43A at 0.8 PF. On a 3 phase 400V supply it's 1.44A per phase at unity, or 1.80A per phase at 0.8 PF.

How do I find amps from kW?

Divide the watts (kW × 1000) by the voltage and the power factor. For 3 phase, also divide by 1.732. The calculator above does it for you.

How many amps does a 100 kW generator produce?

At 400V 3 phase and 0.8 PF, a 100 kW generator delivers about 180.4A per phase at full load.

Why does the power factor change the amps?

A lower power factor means more current flows for the same useful power. At PF 0.8, a load draws 25% more current than the same kW at PF 1.0.

Is converting kW to current the same as kW to amps?

Yes. Current is measured in amps (amperes), so a kW to current conversion and a kW to amps conversion are the same calculation.

How do I convert amps back to kW?

Use our Amps to kW calculator. For 3 phase, kW = 1.732 × amps × volts × PF ÷ 1000.

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