What this converter does
This converter turns apparent power in kVA into line current in amps for single-phase and three-phase circuits — the figure used to size transformers, generators and breakers. Enter the voltage, pick the phase, and read the current. Swap the arrow to work back from amps.
Apparent power uses no power factor: current is simply the kVA over the voltage, with a √3 factor for three-phase. For real power in kilowatts instead, see the kW to Amps converter, which does take power factor.
The units it covers
Current from apparent power depends only on the phase and the voltage — no power factor is involved.
View all units & their values
| Unit | Symbol | Value | Mainly used |
|---|---|---|---|
| Apparent power | kVA | S | Transformer and generator rating |
| Line current | A | I | What the conductor carries |
| Voltage | V | V | Line-to-line for three-phase |
| √3 factor | √3 | 1.732 | Applies to three-phase only |
The formula
Current is apparent power over voltage, with √3 for three-phase:
A = kVA × 1000 ÷ (√3 × V) — drop √3 for single-phaseWhere:
- kVA = apparent power
- V = supply voltage (line-to-line for 3-phase)
- √3 = 1.732, the three-phase factor
Worked example
A 100 kVA three-phase transformer at 400 V. Find the full-load current.
A = kVA × 1000 ÷ (√3 × V)100000 ÷ (1.732 × 400) = 144.3 AThe transformer’s full-load current is about 144 A per line.
The units in this example
The total power a supply must deliver, used to rate transformers and generators. Divided by voltage (and √3 for three-phase) it gives the line current.
- A = kVA × 1000 ÷ V — 1ph
- A = kVA × 1000 ÷ (√3 × V) — 3ph
- 100 kVA, 400 V, 3ph = 144 A
- 1 MVA = 1,000 kVA
The amperes in each line conductor. It sizes cables and protection, and depends only on kVA and voltage — power factor does not enter.
- kVA = √3 × V × A ÷ 1000 — 3ph
- kVA = V × A ÷ 1000 — 1ph
- 1 A at 400 V, 3ph = 0.69 kVA
- √3 = 1.732