Field Duct Sizing Chart
Get instant duct size recommendations based on required CFM
Instructions for Use
- Identify the volume of air (CFM) that will be passing through the duct
- Select the duct type (Round or Rectangular)
- Check any special conditions (long runs or excessive transitions)
- Click "Find Duct Size" to get recommendations
- If desired airflow exceeds the CFM rating, increase to the next duct size
- Always prove design by test and balance
Recommended duct sizes for 0 CFM
Round Duct Reference (Flexible or Round Metal Pipe)
| Duct Size | Design CFM | Notes |
|---|
Note: Flex duct = .05" on most metal duct calculators | Round metal pipe = .06" on most metal duct calculators
Rectangular Duct Reference (Sheet Metal)
| Height | 4" Wide | 6" Wide | 8" Wide | 10" Wide | 12" Wide |
|---|
Note: Rectangular sheet metal duct = .07" on most metal duct calculators