What this converter does
This converter turns line current in amps into apparent power in kVA for single-phase and three-phase circuits — handy for reading an existing load off a clamp meter and sizing the supply. Enter the voltage, pick the phase, and read the kVA. Swap the arrow to go back to amps.
No power factor is needed: apparent power is just voltage times current, scaled by √3 for three-phase. For real power in kilowatts, use the Amps to kW converter, which applies power factor.
The units it covers
Apparent power from current depends only on the phase and voltage — power factor plays no part.
View all units & their values
| Unit | Symbol | Value | Mainly used |
|---|---|---|---|
| Line current | A | I | Measured at the conductor |
| Apparent power | kVA | S | Transformer and generator rating |
| Voltage | V | V | Line-to-line for three-phase |
| √3 factor | √3 | 1.732 | Applies to three-phase only |
The formula
Apparent power is voltage times current, with √3 for three-phase:
kVA = √3 × V × A ÷ 1000 — drop √3 for single-phaseWhere:
- A = the measured line current
- V = supply voltage (line-to-line for 3-phase)
- √3 = 1.732, the three-phase factor
Worked example
A three-phase line draws 144 A at 400 V. Find the apparent power.
kVA = √3 × V × A ÷ 10001.732 × 400 × 144 ÷ 1000 = 99.8 kVAThe load is about 100 kVA — the rating a transformer would need.
The units in this example
The amperes flowing in each conductor, read from a meter or nameplate. Multiplied by voltage (and √3 for three-phase) it gives apparent power.
- kVA = V × A ÷ 1000 — 1ph
- kVA = √3 × V × A ÷ 1000 — 3ph
- 144 A, 400 V, 3ph = 100 kVA
- √3 = 1.732
The total power the supply must carry, used to size transformers, generators and switchgear. It ignores power factor because the phase angle is already built in.
- A = kVA × 1000 ÷ V — 1ph
- A = kVA × 1000 ÷ (√3 × V) — 3ph
- 1 kVA, 400 V, 3ph = 1.44 A
- 1 MVA = 1,000 kVA