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Calcimator

Motor Starting Current Calculator

Calculate motor full load amps, starting inrush current, voltage drop during starting, and starting KVA demand.

Inputs

HP
V
× FLA
phase

Results

Full Load Amps (FLA)

57.37 A

Starting Current (LRA)

344.23 A

Estimated Voltage Drop10.33%
Starting KVA Demand286.19 kVA
How to Use This Calculator
  1. Enter the Motor Horsepower from the nameplate and the Motor Voltage (e.g., 208, 480, or 4160 V).
  2. Enter the Motor Efficiency at full load — typically 0.88–0.96 for standard NEMA motors.
  3. Set the Starting Current Multiplier: direct-on-line (DOL) starting ≈ 6–8×, soft starter ≈ 2–4×, VFD ≈ 1–1.5× FLA.
  4. Select the Number of Phases (1 or 3).
  5. Read the Full Load Amps (FLA) to size cables and overload protection, and the Starting Current (LRA) to size upstream breakers and transformers.
  6. Check the Estimated Voltage Drop % during starting — values above 5% can trip sensitive controls; above 10% may prevent motor start.
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