How this calculator works
Kilowatts are thousands of watts, so the current is the power in watts divided by the voltage and the power factor. A three-phase supply carries the same power on three wires, which divides the current by √3 (1.732) for the line-to-line voltage.
Worked example: 10 kW on a single-phase 240 V supply at a power factor of 1 draws 41.7 A, so it needs a 60 A breaker for a continuous load. At a power factor of 0.8 it draws 52.1 A (12.50 kVA). The same 10 kW on three-phase 208 V draws 27.8 A, and 100 kW at 480 V three-phase draws 120.3 A.
kW to amps
Power factor 1. Single-phase 240 V, and three-phase 208 V and 480 V.
| kW | 240 V single-phase | 208 V three-phase | 480 V three-phase |
|---|---|---|---|
| 1 kW | 4.2 A | 2.8 A | 1.2 A |
| 3 kW | 12.5 A | 8.3 A | 3.6 A |
| 5 kW | 20.8 A | 13.9 A | 6.0 A |
| 7.5 kW | 31.3 A | 20.8 A | 9.0 A |
| 10 kW | 41.7 A | 27.8 A | 12.0 A |
| 15 kW | 62.5 A | 41.6 A | 18.0 A |
| 20 kW | 83.3 A | 55.5 A | 24.1 A |
| 30 kW | 125.0 A | 83.3 A | 36.1 A |
| 50 kW | 208.3 A | 138.8 A | 60.1 A |
| 100 kW | 416.7 A | 277.6 A | 120.3 A |
Tips before you buy
- Three-phase supplies the same power with 58% of the current per wire, which is why large motors and buildings use it.
- Always use the line-to-line voltage for three-phase: 208 V, 400 V or 480 V, not the 120 V or 277 V to neutral.
- A generator rated in kVA gives kW = kVA × power factor. A 10 kVA generator at 0.8 gives 8 kW.
- Size the breaker for 125% of a continuous load, and the wire for the breaker.
- Ask your utility or the equipment label which voltage and phase you actually have.
Tools & materials for this project
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Frequently asked questions
How do you convert kW to amps?
Divide the watts (kW × 1,000) by the voltage and the power factor. 10 kW on 240 V single-phase is 41.7 A.
How many amps is 10 kW?
41.7 amps on 240 V single-phase, 83.3 amps on 120 V, and 27.8 amps on 208 V three-phase, at a power factor of 1.
How many amps is 5 kW?
20.8 amps on 240 V single-phase, and 41.7 amps on 120 V.
How many amps is 100 kW?
120.3 amps on 480 V three-phase, and 277.6 amps on 208 V three-phase.
How do you convert kVA to kW?
Multiply kVA by the power factor. A 10 kVA generator at a power factor of 0.8 delivers 8 kW.
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