basic

Motor Locked-Rotor Starting Current Calculator

I_start ≈ kVA_code × S_rated / V_line — motor inrush current.

Estimates motor starting (locked-rotor) current from rated kW, voltage, full-load current, and starting current multiplier (6×–8×).

Marcus Laurent By Marcus Laurent
Published Last reviewed 1 min read

Inputs

Results

Enter values and click Calculate to see results.
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How to use this calculator

  1. Fill in the inputs above using the units you already have.
  2. Values update automatically as you type — no submit button needed.
  3. Hover any result row for the underlying formula and intermediate values.

Formula

I_start = I_FLA × LRC_multiplier; I_FLA = P×1000/(√3×V×pf×η)

In depth

Estimates motor starting (locked-rotor) current from rated kW, voltage, full-load current, and starting current multiplier (6×–8×).