Dust Collector Main Duct Calculator
Main trunk sizing for a shared dust collection system.
Enter your values
ⓘ Live results
Results
- Main duct design CFM
- 600 CFM
- Main duct diameter
- 5.2 in
- Collector sizing
- Select a collector rated for at least 690 CFM at expected static
- Note
- Static pressure adds up through the longest branch run — verify with the collector's fan curve
Quick answer
The main trunk duct should be sized for the largest simultaneous CFM demand (usually the biggest single machine, or two if run together) at 3500-4500 FPM.
Main CFM = max simultaneous branch demand; diameter from CFM and velocity
How to use the Dust Collector Main Duct Calculator
- 1List the CFM requirement of each machine on the system.
- 2Decide how many run simultaneously in practice.
- 3Size the main trunk for the simultaneous total, and pick a collector rated above that with margin.
Worked example
Using the values the calculator loads with:
Inputs
- Machine 1 CFM600 CFM
- Machine 2 CFM400 CFM
- Machines run simultaneously1
- Transport velocity4000 FPM
Results
- Main duct design CFM600 CFM
- Main duct diameter5.2 in
- Collector sizingSelect a collector rated for at least 690 CFM at expected static
- NoteStatic pressure adds up through the longest branch run — verify with the collector's fan curve
Frequently asked questions
Do I size for every machine running at once?
Rarely necessary in a small shop — size for the realistic worst case, usually 1-2 machines running together.
What if my collector is undersized?
Airflow and static pressure both suffer, leading to poor capture and duct clogging at the far end of the system.
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.