HVAC Filter Sizing Calculator — Formule
## Filter Sizing
**Face Area = CFM / Face Velocity**
**Filters = Face Area / Single Filter Area**
Keeping face velocity under 300 ft/min ensures good filtration and low pressure drop. Higher velocities reduce filter life and may blow dust through the media.
**Face Area = CFM / Face Velocity**
**Filters = Face Area / Single Filter Area**
Keeping face velocity under 300 ft/min ensures good filtration and low pressure drop. Higher velocities reduce filter life and may blow dust through the media.
Exemple Résolu
1,200 CFM system, 300 ft/min max, using 20x25 inch filters.
- Min face area = 1200 / 300 = 4.0 sq ft
- Filter area = 20 x 25 / 144 = 3.47 sq ft
- Filters = ceil(4.0 / 3.47) = 2
- Actual velocity = 1200 / (2 x 3.47) = 173 ft/min