Engineering CalculationMotor Full Load Current Calculator (3-phase, kW to Amps)
Find the full load current (FLC) of an induction motor from its kW rating, voltage, power factor and efficiency, then carry it straight into breaker, overload relay, cable and starter selection.
Open the calculator →Formula
I = (P × 1000) / (√3 × V × cosφ × η) (3-phase)
I = (P × 1000) / (V × cosφ × η) (1-phase)
P = motor output in kW, V = line voltage, cosφ = power factor, η = efficiency
Worked example
15 kW motor, 415 V, power factor 0.85, efficiency 0.90
I = 15000 / (1.732 × 415 × 0.85 × 0.90) = 27.3 A
Where engineers use it
- Motor feeder design for MCC panels
- Selecting overload relay range and MPCB
- Cable sizing from the motor rating
How to use
- Click Open the calculator. It runs free in your browser, on desktop or phone.
- Enter your values. Units and typical ranges are shown next to each input.
- Read the result and the step-by-step working, then print or add it to your Project BOQ.
Questions
What power factor and efficiency should I use?
Use the motor nameplate or the maker's data sheet. If those are not available, the guided check in the suite asks for them and shows the effect on current.
Does it cover HP rating?
Yes. Enter HP and the tool converts using 1 HP = 0.746 kW.