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kVA / Amps Conversion Calculator

Use this calculator to quickly convert amps to kVA, or convert kVA to amps. Simply enter in the voltage and whichever you know to get the other.

kVA & Amps Calculator

Note: A three-phase circuit assumes line to line voltage. Typical line to line voltage in the UK is 400V, while line to neutral is 230V. 

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How to Convert Between Amps and kVA manually

Converting between kVA and Amps is a fundamental calculation used to relate a system’s apparent power (kVA) to its current (Amps).

In simple terms, these formulas help you find the Amps required to safely size cables and fuses for a piece of equipment, or you can find the total kVA of a load to correctly size a supply like a transformer or generator.

Single-Phase: kVA to Amps

Amps = kVA × 1000 Volts

Single-Phase: Amps to kVA

kVA = Amps × Volts 1000

Three-Phase: kVA to Amps

Amps = kVA × 1000 V L - L × 3

Three-Phase: Amps to kVA

kVA = V L - L × Amps × 3 1000

Breakdown of Terms

    • kVA — This is the apparent power of a system. It’s the value you often find on the nameplate of transformers or generators, measured in kilovolt-amps.
    • Amps (I) — This is the electrical current. It represents the flow of electricity that the circuit wiring will carry, measured in Amperes (A).
    • Volts (V) — This is the system voltage. Depending on the circuit, this will either be the line-to-neutral voltage (e.g., 230V) or the line-to-line voltage (e.g., 400V).
    • Circuit Type — This determines if the calculation is for a single-phase or three-phase system, which uses a different formula.

Single-Phase Example

Let’s say a large workshop circuit is drawing a total measured current of 63 Amps. We need to find its total kVA to ensure the supply is adequate.

  • Amps (I): 63A
  • Volts (V): 230V
  • Formula: kVA = (I × V) / 1000

Calculation:

  1. kVA = (63 × 230) / 1000
  2. kVA = 14,490 / 1000
  3. kVA = 14.49 kVA

The total load on the circuit is 14.49 kVA.

Three-Phase Example

A small industrial unit has a three-phase machine, and the current measured on each line is 32 Amps. We want to find its power in kVA.

  • Amps (I): 32A

  • Line-to-Line Volts (V_L-L): 400V

  • Formula: kVA = (V_L-L × I × √3) / 1000

Calculation:

  1. kVA = (400 × 32 × 1.732) / 1000

  2. kVA = 22,169.6 / 1000

  3. kVA = 22.17 kVA

The apparent power of the machine is 22.17 kVA.

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