How Many Amps Is 100 kVA at 400V?

At 400V, a 100 kVA three-phase load draws 144.34 amps per line. kVA is apparent power, so the current is set by kVA and the voltage alone, without a power-factor term. The equivalent single-phase current at this voltage is 250 amps.

100 kVA equals 144.34 amps at 400 volts (three-phase, L-L)

144.34 Amps

Single Phase (400V)250 A

Try: 75kVA at 400V 50kVA at 400V 150kVA at 400V 40kVA at 400V

kVA

Volts

Amps (3Φ per line)

144.34

Assumes an AC three-phase line-to-line circuit at the input voltage. kVA is apparent power, so no power factor term is involved.

Formulas

Single Phase

I_(A) = (kVA × 1000) ÷ V

(100 × 1000) ÷ 400 = 100,000 ÷ 400 = 250 A

Three Phase (400V Line-to-Line)

I_(A) = (kVA × 1000) ÷ (V_L-L × √3)

100,000 ÷ (400 × 1.732) = 100,000 ÷ 692.8 = 144.34 A

Applies to 400/230 systems where 400V is the line-to-line voltage.

Single Phase vs Three Phase

The same 100 kVA unit draws very different current depending on the phase configuration:

Configuration	Formula	Current at 400V
Single Phase	100,000 ÷ 400	250 A
Three Phase (400V L-L)	100,000 ÷ (400 × √3)	144.34 A

For this specific case, 100 kVA at 400V, three-phase carries about 42.26% less current per line than single-phase at the same voltage. That gap tracks the 1 ÷ √3 factor for L-L three-phase (or 1 ÷ 3 for L-N), which is why three-phase distribution is common at commercial and industrial scale: the same apparent power rides on smaller conductors and smaller breakers (applies to 400/230 systems).

Generator & UPS Sizing

Load-Side Real Power by Power Factor

A load with an apparent power of 100 kVA draws different amounts of real power depending on the load's own power factor. The table below is a load-side conversion, not a forecast of what a generator or UPS will output for that load: generators and UPS units publish their own independent kW rating set by the engine or inverter design, and that rating is often lower than kVA × the load's PF.

Load Type	Load PF	Load Real Power (kW)	Current at 400V (three-phase, per line)
Resistive (heaters, lights)	1.0	100 kW	144.34 A per line
Mixed typical	0.85	85 kW	144.34 A per line
Motors/HVAC	0.80	80 kW	144.34 A per line
Computers/servers (no PFC)	0.65	65 kW	144.34 A per line

Note: current draw stays the same across the rows because kVA sets the current, not the load's power factor. PF only affects how much real work (kW) the load does per amp drawn.

Sizing a load against a source. If you are feeding this load from a UPS, generator, or transformer, check the load against both the source's kVA rating AND the source's kW rating. Those are two independent numbers published by the manufacturer. A 10 kVA / 8 kW generator, for example, can supply up to 10 kVA of apparent power AND up to 8 kW of real power, whichever limit is reached first. Do not use the kW figures above as a substitute for the source's published kW rating.

Circuit Sizing: Starting Points

The numbers below are rough order-of-magnitude starting points under typical assumptions (copper conductors, 75°C terminations, short run, no ambient or bundling derates, non-continuous duty). They are not install specs. Actual breaker and wire selection depends on the equipment nameplate, conductor and termination temperature ratings, cable type, run length and voltage-drop target, ambient and bundling conditions, whether the load is continuous, any NEC 430/440 motor or HVAC provisions, and local code.

	Single Phase	Three Phase
Current draw (at full kVA)	250 A	144.34 A
Ballpark branch OCP	~250A	~150A

For a real install, run the full wire-size calculator with your actual run length, voltage, and drop target, and verify breaker selection against the equipment nameplate and local code.

Energy Cost at Full Load

A load with an apparent power of 100 kVA at load PF 0.85 draws 85 kW of real power. Running cost at that draw: $14.45/hour at $0.17/kWh (rates last reviewed April 2026), or $3,468.00/month (8h/day). Full breakdown.

kW Equivalent

100 kVA at PF 0.85 = 85 kW. See 85 kW to amps at 400V.

Other kVA Ratings at 400V

kVA	Three Phase Amps (L-L, per line)	Single Phase Amps	Real Power (PF 0.8)
5 kVA	7.22 A	12.5 A	4 kW
7.5 kVA	10.83 A	18.75 A	6 kW
10 kVA	14.43 A	25 A	8 kW
15 kVA	21.65 A	37.5 A	12 kW
20 kVA	28.87 A	50 A	16 kW
25 kVA	36.08 A	62.5 A	20 kW
30 kVA	43.3 A	75 A	24 kW
40 kVA	57.74 A	100 A	32 kW
50 kVA	72.17 A	125 A	40 kW
75 kVA	108.25 A	187.5 A	60 kW
100 kVA	144.34 A	250 A	80 kW
150 kVA	216.51 A	375 A	120 kW

Frequently Asked Questions

How many amps is 100 kVA at 400V?expand_more

100 kVA at 400V is 144.34 amps per line on a three-phase circuit (400/230), or 250 amps on single-phase at the same voltage.

What is the difference between kVA and kW?expand_more

kVA is apparent power (V×I), which sets the current on the circuit and the sizing of conductors, breakers, and windings. kW is real power (the portion that does useful work), equal to kVA×load PF. A load with an apparent power of 100 kVA at load PF 0.8 draws 80 kW of real power. For a source such as a generator or UPS, kVA and kW are two independent manufacturer ratings, not two views of the same spec, and both have to be checked when sizing a load.

Why are UPS and generators rated in kVA not kW?expand_more

Because the current on the output (and therefore the conductor, switchgear, and winding sizing) is set by apparent power, kVA = V×I, regardless of the load's power factor. UPS and generator manufacturers publish a separate kW rating in addition to the kVA rating, set by the inverter or engine design, and it is often lower than the kVA rating. You cannot derive a UPS or generator's kW output from its kVA rating and the load's power factor: the two ratings are independent specs and a load has to fit under each of them when sizing against the source.

Can a 100 kVA generator run my whole house?expand_more

A 100 kVA unit can typically handle a full house including central AC, provided simultaneous motor starting is managed and the actual connected load fits. An electrician should run an NEC 220 load calc against your specific panel before committing to a size.

Three-phase vs single-phase for 100 kVA?expand_more

Three-phase (400/230) draws 144.34A per line. Single-phase at the same voltage draws 250A. Three-phase delivers the same apparent power across three conductors, so each line carries less current and the wire and breakers can be smaller for the same kVA.

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.