Air Velocity Calculator
Calculate velocity, CFM, or duct area from known values.
Velocity Formula
V = CFM ÷ Area (sq ft)
Where: V = velocity (FPM), CFM = airflow (ft³/min), Area = duct cross-sectional area (ft²)
Maximum Velocities (FPM)
| Application | Residential | Commercial |
|---|---|---|
| Main Supply Duct | 700-900 | 1000-1300 |
| Branch Supply | 600-700 | 800-1000 |
| Supply Outlet | 500-750 | 500-750 |
| Main Return | 500-600 | 800-1000 |
| Branch Return | 400-500 | 600-800 |
| Return Grille | 300-500 | 400-600 |
Higher velocities = more noise and higher static pressure. Keep residential supply under 900 FPM for quiet operation.