Printable CFM Duct Sizing Calculator
This sheet is for HVAC installers, techs, and anyone sizing round duct runs by airflow. It includes a duct sizing calculator with columns for Room/run, CFM, Friction rate, Round diameter in inches, and Velocity at the next whole-inch size. Sample rows include Bedroom 1 at 120 CFM and Living room at 400 CFM, both with a 0.1 friction rate entry.
Free printable · PDF
- 1 page
- US Letter — choose “Fit to page” for A4
- PDF, 62 KB
Free for personal, family and classroom use.
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Enter the CFM and friction rate for each run, then read the exact round diameter in column D and the velocity for the next whole-inch size in column E. Use it to compare duct sizes, check air velocity, and keep sizing notes in one place.
Good for
- Size round duct runs by room airflow
- Check velocity at the next inch size
- Keep duct sizing notes on one page
Tip: Print at actual size so the worksheet grid stays easy to read and fill in.
4 files · PDF, XLSX, DOCX
Get every sheet: Duct Sizing Reference Pack
This sheet plus 3 more in one download, with the editable Excel and Word files. Printable round duct CFM chart at five friction rates, rectangular equivalents table, an Excel duct sizing calculator and a room-by-room airflow worksheet.
$3.00 USD, one-time 4 files · about $0.75 each
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