Propeller Fan CFM Calculator
Free-air CFM of a propeller (axial) fan from disk area and velocity.
Enter your values
ⓘ Live results
Results
- Free-air CFM
- 3,770 CFM
- Swept area
- 3.14 sq ft
- Note
- Free-air estimate — CFM drops quickly against added static pressure
Quick answer
Propeller fan CFM equals the fan's swept disk area multiplied by the average discharge air velocity.
CFM = Area x V
How to use the Propeller Fan CFM Calculator
- 1Enter the propeller fan's blade tip diameter and its measured or rated discharge velocity.
- 2Read the estimated free-air CFM (no ductwork resistance).
- 3Remember propeller fans lose CFM fast once any static pressure is added — check the manufacturer's curve for ducted applications.
Worked example
Using the values the calculator loads with:
Inputs
- Blade diameter24 in
- Average discharge velocity1200 FPM
Results
- Free-air CFM3,770 CFM
- Swept area3.14 sq ft
- NoteFree-air estimate — CFM drops quickly against added static pressure
Frequently asked questions
Can propeller fans handle ductwork?
Only very short, low-resistance duct runs — for real ductwork, use a vane-axial or centrifugal fan instead.
Where are propeller fans used?
Wall or roof exhaust with no ductwork, or condenser/cooling tower fans discharging to open air.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.