Industrial Fans, Blowers & Air Movement Equipment calculator

Motor Sizing Calculator

Use this calculator to create an early motor sizing estimate for industrial fans and blowers. It gives engineers and estimators a quick way to combine airflow, static pressure, conversion basis, and service margin before confirming the duty point on a fan curve.

What this calculator does

  • Estimate fan motor sizing from airflow, static pressure, a power conversion basis, and service factor.
  • Use it when selecting a motor size for centrifugal fans, axial fans, blowers, or exhaust systems before checking final brake horsepower.
  • The result is an early motor size estimate for a fan or blower duty point.

Formula used

  • Estimated motor size = design airflow × design static pressure × power conversion basis × motor service factor or sizing margin
  • Confirm final motor selection against brake horsepower, service factor, temperature rise, and fan curve duty point.

Inputs explained

  • Design airflow: Use the airflow required at the fan inlet or outlet for the selected operating point.
  • Design static pressure: Use external static pressure or total system pressure basis consistently with your sizing method.
  • Power conversion basis: Use the conversion basis from your estimating standard, fan law model, or preliminary sizing worksheet.
  • Motor service factor or sizing margin: Apply the motor service factor, drive loss allowance, altitude allowance, or engineering sizing margin.

How to use the result

  • Use it for quote screening, motor option comparison, and preliminary electrical load planning.
  • Final selection should be checked against manufacturer fan curves, brake horsepower, altitude, temperature, and applicable motor standards.

Common questions

  • What is the motor sizing calculator for? It estimates the motor size needed for a fan or blower duty point.
  • What information should I enter? Use design airflow, static pressure, conversion basis, and service factor or sizing margin.
  • What does the result tell me? The result helps compare motor options before final fan curve and brake horsepower review.
  • When is the result only an estimate? It is only an estimate when fan efficiency, density, drive losses, or actual operating point changes.

Last reviewed 2026-05-12.