"How many amps is a 400 kVA generator?" and "750 kVA generator full load current" are some of the most common questions we get. The answer takes one formula — and it decides the breaker, the ATS panel and the cables.
The kVA to amps formula
For a three-phase generator:
Full load current (A) = kVA × 1000 ÷ (√3 × voltage)
At 400 V that simplifies to amps ≈ kVA × 1.443. At 415 V multiply by 1.391; at 380 V by 1.519.
For a single-phase set: amps = kVA × 1000 ÷ 230.
And to go from kW: kVA = kW ÷ power factor (0.8 for generator ratings).
Generator full load current chart (400 V, 3-phase, 0.8 PF)
| Generator | kW | Full-load current |
|---|---|---|
| 10 kVA | 8 kW | 14 A |
| 20 kVA | 16 kW | 29 A |
| 30 kVA | 24 kW | 43 A |
| 40 kVA | 32 kW | 58 A |
| 60 kVA | 48 kW | 87 A |
| 80 kVA | 64 kW | 115 A |
| 100 kVA | 80 kW | 144 A |
| 125 kVA | 100 kW | 180 A |
| 150 kVA | 120 kW | 217 A |
| 200 kVA | 160 kW | 289 A |
| 250 kVA | 200 kW | 361 A |
| 300 kVA | 240 kW | 433 A |
| 400 kVA | 320 kW | 577 A |
| 500 kVA | 400 kW | 722 A |
| 750 kVA | 600 kW | 1083 A |
| 1000 kVA | 800 kW | 1443 A |
| 1500 kVA | 1200 kW | 2165 A |
| 2000 kVA | 1600 kW | 2887 A |
| 2500 kVA | 2000 kW | 3608 A |
So a 400 kVA DG full load current is about 577 A, and a 750 kVA generator full load current is about 1083 A. Each size page in our generator kVA list shows the models that deliver it.
Standby or prime current?
The chart uses the rating you put in. A set rated 550 kVA standby and 500 kVA prime gives about 794 A at its standby rating and 722 A at prime. Size the breaker and cables on the highest current the set can deliver — normally the standby rating.
What the current decides
- Main breaker: chosen at or just above the full-load current, with the right breaking capacity for the site.
- ATS panel: rated for the same current — for example a 63–400 A ATS up to about 250 kVA, and a 630–4000 A ATS for larger sets.
- Cables: sized for the current, the cable run length (voltage drop) and the installation method, by the electrical designer.
- Paralleling: two synchronised sets add their currents, so the common busbar and outgoing breaker carry the total.
Breaking capacity, cable sizes and protection settings depend on the site and on the consultant's and authority's requirements — the chart is for first sizing, not for final design.
From current back to kVA
If you know the current your building draws — from the main breaker or a clamp-meter reading at peak — reverse the formula: kVA = amps × 400 × 1.732 ÷ 1000. A building peaking at 300 A on 400 V needs about 208 kVA running; add headroom and motor starting, and a 250 kVA set is the usual answer. Our kVA calculator does the rest.
Need help matching current to a generator?
Send us the main breaker rating or a load schedule on WhatsApp. We will match it to the right generator, ATS and switchgear and send a quotation.
