kW to Amps Converter
Convert kilowatts to amps for single and three-phase circuits
Reference Info & Formulas
Single Phase
I = (kW × 1000) / (V × PF)
Three Phase
I = (kW × 1000) / (√3 × V × PF)
Single phase: 230V
Three phase: 400V
PF 1.0: Resistive loads (heaters, showers)
PF 0.85: Motor loads
Data: Standard electrical formulas (P = V × I × PF)
For guidance only. The responsibility for any electrical installation lies with the qualified person carrying out the work. Always verify calculations independently and apply professional judgement.
How This Calculator Works
Converting kilowatts to amps requires knowing the supply voltage and the power factor of the load.
For single-phase AC circuits, the current is found by dividing the real power by the product of voltage and power factor. For purely resistive loads such as heaters and kettles, the power factor is 1.0. For motors and transformers, it is typically 0.8 to 0.85, meaning the circuit carries more current than the real power alone would suggest.
I = P / (V × PF)- I
- = Current in amps
- P
- = Real power in watts
- V
- = Supply voltage (230V UK single-phase)
- PF
- = Power factor (1.0 for resistive loads)
IET Guidance Note 1
For three-phase loads, the formula becomes I = P / (√3 × V × PF), where V is the line-to-line voltage of 400V.
Quick Reference — kW to Amps at 230V
Common appliance ratings and equivalent amps (PF = 1.0)
| Power (kW) | Current (A) | Typical Application |
|---|---|---|
| 1 | 4.3 | Small appliance, fan heater |
| 2 | 8.7 | Towel rail, small water heater |
| 3 | 13.0 | Immersion heater, kettle |
| 5 | 21.7 | Small cooker, instantaneous water heater |
| 7.5 | 32.6 | Electric shower (7.5kW) |
| 10 | 43.5 | Electric shower (10kW) |
| 15 | 65.2 | Large range cooker |
Values assume 230V single-phase and unity power factor. Motor loads will draw higher current due to PF < 1.
Practical Notes
Use kW, Not kVA
Quick Mental Arithmetic
Frequently Asked Questions
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