Free Engineering Tool

Motor Sizing Calculator

Calculate required motor power from load parameters and get recommended standard IEC motor size with starting current and torque estimates.

IEC Standard Sizes0.37 – 315 kWDOL / Y-Δ / VFD

Load Type

Input Mode

Load Value (kW)

Required Speed (RPM)

Service Factor

Starting Method

Motor Selection

Recommended Standard Motor

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Required Power (with SF)

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Load Torque

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Starting Current (est.)

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Starting Torque Ratio

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Motor Utilization

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Motor Power Calculation

P_required = P_load × Service Factor or P = T × n / 9550

IEC Standard Motor Sizes (kW)

Range	Available Sizes (kW)
Small	0.37, 0.55, 0.75, 1.1, 1.5, 2.2, 3.0, 4.0
Medium	5.5, 7.5, 11, 15, 18.5, 22, 30, 37
Large	45, 55, 75, 90, 110, 132, 160, 200, 250, 315

Starting Current Multipliers

DOL — 6–8× rated current
Star-Delta — 2–3× rated (÷3 of DOL)
Soft Starter — 2–4× rated
VFD — 1–1.5× rated

ℹ️ Tip: Always select the next standard size above the calculated requirement. Oversizing by one step provides thermal margin and longer bearing life.

Motor Sizing Calculator | Load → Motor Selection

Published by Nikolai Shelkovenko on February 15, 2026 February 15, 2026

Motor Selection

Motor Power Calculation

IEC Standard Motor Sizes (kW)

Starting Current Multipliers