Dust Collection CFM Calculator
Workshop dust collector sizing by machine.
Enter your values
ⓘ Live results
Results
- Collector size needed
- 700 CFM
- Duct velocity
- 4,840 FPM
- Transport verdict
- Higher than needed — upsize duct to cut static
- Duct area
- 0.136 sq ft
- Ideal duct diameter
- 5.5 in
Quick answer
Each machine has a port CFM requirement, and duct velocity must stay above 3,500–4,000 FPM to keep chips moving.
CFM = sum of active machine requirements; velocity = CFM / duct area
How to use the Dust Collection CFM Calculator
- 1Enter the CFM demand of the biggest machine you run.
- 2Add a second machine only if you genuinely run two at once.
- 3Check that duct velocity stays between 3,500 and 4,500 FPM.
Worked example
Using the values the calculator loads with:
Inputs
- Largest machine requirement600 CFM
- Second machine (if run together)0 CFM
- Main duct diameter5 in
- Duct leakage allowance10 %
Results
- Collector size needed700 CFM
- Duct velocity4,840 FPM
- Transport verdictHigher than needed — upsize duct to cut static
- Duct area0.136 sq ft
- Ideal duct diameter5.5 in
Frequently asked questions
Why is velocity so critical?
Below about 3,500 FPM heavy chips drop out of the airstream and block the duct.
Is a shop vac enough?
A shop vac gives high suction but only 60–150 CFM — fine for sanders, useless for a table saw.
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.