About this calculator
Power factor matters for motors, pumps and ACs; heaters and bulbs have a power factor of 1.
How to use it
- Choose the supply.
- Choose power or current.
- Enter the values.
The formula
Single phase: P = V × I × PF; three phase: P = √3 × V × I × PF
- V
- voltage (line to line for three phase)
- I
- current
- PF
- power factor
Worked example
A 7.5 kW three-phase motor at 415 V, PF 0.9
- I = 7,500 ÷ (1.732 × 415 × 0.9) = 11.6 A per line.
What the result means
kW is the real power you pay for; kVA is what the wiring and transformer must carry.
Assumptions
- Balanced three-phase loads.
Limitations
- Starting currents of motors are several times higher; size breakers with that in mind.
Frequently asked questions
How many amps is 1 kW at 230 V?
About 4.35 A at power factor 1.
What is power factor?
The ratio of real power (kW) to apparent power (kVA).
How do I convert kW to kVA?
Divide by the power factor.
Last reviewed on 6 October 2026. Found a mistake? Tell us.