How Many Amps Is 25 kW at 400V?

25 kilowatts at 400V works out to roughly 42.45 amps on AC three-phase at PF 0.85. That is typical for commercial HVAC, industrial motors, rooftop units, and three-phase panel loads. See the DC and alternate-phase numbers below for other circuit types.

25 kW at 400V, AC three-phase (PF 0.85)

42.45 Amps

25 kilowatts at 400V on AC three-phase ≈ 42.45 amps

AC Single Phase (PF 0.85)73.53 A

DC (ideal baseline)62.5 A

Try: 22kW at 400V 20kW at 400V 30kW at 400V 18kW at 400V

Volts

Amps (AC three-phase, PF 0.85)

42.45

Formulas

DC: kW to Amps

I_(A) = 1000 × P_(kW) ÷ V_(V)

1000 × 25 ÷ 400 = 25,000 ÷ 400 = 62.5 A

AC Single Phase (PF = 0.85)

I_(A) = 1000 × P_(kW) ÷ (PF × V_(V))

25,000 ÷ (0.85 × 400) = 25,000 ÷ 340 = 73.53 A

AC Three Phase (PF = 0.85)

I_(A) = 1000 × P_(kW) ÷ (√3 × PF × V_L-L), where V_L-L is the line-to-line voltage

25,000 ÷ (1.732 × 0.85 × 400) = 25,000 ÷ 588.88 = 42.45 A

Equipment & Circuit Sizing

Breaker Sizing

Breaker ratings are in amps, not watts, so the real install answer depends on the equipment nameplate FLA, whether the load is continuous (NEC 210.19(A) sizes the conductor and OCP at 125% of a continuous load, equivalently 80% of breaker rating), conductor ampacity and temperature rating, ambient and bundling derates, and any motor or HVAC provisions (NEC 430 / 440). At roughly 42.45A on AC three-phase at 400V, the load sits in the bracket between a 45A standard size (non-continuous) and the next size up that covers a continuous load under 210.19(A) (around 60A). The actual install pick depends on whether the load is continuous and the factors above; a conversion page can't pick a single "right" breaker from the amp draw alone.

Energy Cost

25 kW costs $4.25/hour at $0.17/kWh (rates last reviewed April 2026). See breakdown.

Power Factor Reference (AC three-phase)

How the line current for 25 kW at 400V changes with load power factor, on the same AC three-phase circuit basis the rest of the page uses. DC has no power factor; PF 1.0 represents resistive AC loads.

Load Type	PF	25 kW at 400V (AC three-phase)
Resistive (heaters, incandescent)	1	36.08 A
Fluorescent lamps	0.95	37.98 A
LED lighting	0.9	40.09 A
Synchronous motors	0.9	40.09 A
Typical mixed loads	0.85	42.45 A
Induction motors (full load)	0.8	45.11 A
Computers (without PFC)	0.65	55.51 A
Induction motors (no load)	0.35	103.1 A

AC Conversion Comparison

On DC, 25kW at 400V draws 62.5A. AC single-phase at PF 0.85 pulls 73.53A because reactive current is added on top of the real power. Three-phase at the same voltage needs only 42.45A per line since the same 25kW is shared across three conductors instead of one.

Circuit Type	Formula	Result
DC	25,000 ÷ 400	62.5 A
AC Single Phase (PF 0.85)	25,000 ÷ (0.85 × 400)	73.53 A
AC Three Phase (PF 0.85)	25,000 ÷ (1.732 × 0.85 × 400)	42.45 A

Other kW Values at 400V

kW	AC 3-Phase per line, PF 0.85	AC 1-Phase PF 0.85
4 kW	6.79 A	11.76 A
5 kW	8.49 A	14.71 A
6 kW	10.19 A	17.65 A
7.5 kW	12.74 A	22.06 A
8 kW	13.58 A	23.53 A
10 kW	16.98 A	29.41 A
12 kW	20.38 A	35.29 A
15 kW	25.47 A	44.12 A
18 kW	30.57 A	52.94 A
20 kW	33.96 A	58.82 A
22 kW	37.36 A	64.71 A
25 kW	42.45 A	73.53 A
30 kW	50.94 A	88.24 A
35 kW	59.43 A	102.94 A
40 kW	67.92 A	117.65 A

Same kW, Other Voltages

Each destination page leads with the interpretation most common for that voltage, so the amps shown below use the same basis as the page you'd land on: single-phase for residential voltages, three-phase for commercial/industrial panel voltages, DC for low-voltage.

electrical_services 25 kW at 208V = 81.64A (3-phase) electrical_services 25 kW at 220V = 133.69A (1-phase) electrical_services 25 kW at 230V = 127.88A (1-phase) electrical_services 25 kW at 240V = 122.55A (1-phase) electrical_services 25 kW at 460V = 36.91A (3-phase) electrical_services 25 kW at 480V = 35.38A (3-phase) electrical_services 25 kW at 575V = 29.53A (3-phase)

Related Calculations

bolt 25,000W to amps at 400V payments 25,000W running cost cable Wire size for 42.45A at 400V (3Φ)

Frequently Asked Questions

How many amps is 25 kW at 400V?expand_more

25 kW at 400V draws about 42.45 amps on an AC three-phase circuit at PF 0.85. Alternate cases at the same voltage: 62.5A on DC, 73.53A on AC single-phase.

What size breaker would I need for 25 kW at 400V?expand_more

This is a sizing question, not a conversion question, and there is no single correct answer from a page like this. Breaker selection depends on the equipment nameplate FLA, whether the load is continuous (NEC 210.19(A) applies the 125% continuous-load rule), the conductor ampacity and temperature rating, any NEC 430/440 motor or HVAC provisions, and local code interpretation. Use the nameplate and a licensed electrician for the real install value; use this page only for the current-draw estimate that feeds into that process.

What is 25 kW in watts?expand_more

25 kW equals 25,000 watts. Multiply kilowatts by 1000.

How many amps does a 25 kW EV charger draw at 400V?expand_more

400V is commercial/industrial panel voltage, not a typical AC EVSE feed to a vehicle. On three-phase 400V, 25 kW works out to about 42.45A per line (three-phase at PF 0.85). In practice, 400-480V three-phase is usually the AC input to a DC fast charger (50-350 kW CCS/NACS stations like Tesla Superchargers), which rectifies to DC and delivers that directly to the vehicle, rather than an AC EVSE connector. A 25 kW figure at 400V is most likely the AC feed to a smaller commercial cabinet or the control-side input of a larger DC fast charger, not an at-the-car AC current.

How does three-phase affect the amps for 25 kW?expand_more

Three-phase at 400V draws 42.45A per line versus 73.53A single-phase. Less current per conductor means smaller wire and lower I²R losses.

This calculator provides estimates for reference purposes only. Always consult a licensed electrician and verify compliance with the National Electrical Code (NEC) and local electrical codes before performing any electrical work.