Duct Velocity Noise Calculator
Check duct velocity against noise limits.
Enter your values
ⓘ Live results
Results
- Velocity
- 1,100 FPM
- Recommended limit for this location
- 700 FPM
- Status
- Exceeds recommended limit — increase duct size
Quick answer
Recommended maximum duct velocities to avoid noticeable noise range from about 600 FPM near registers to 1500+ FPM in mechanical room trunks.
Velocity = CFM / cross-section area
How to use the Duct Velocity Noise Calculator
- 1Enter the duct's airflow and diameter to calculate velocity.
- 2Select where the duct segment is located, since noise tolerance differs by room type.
- 3Compare the calculated velocity against the recommended limit for that location.
Worked example
Using the values the calculator loads with:
Inputs
- Airflow600 CFM
- Duct diameter10 in
- Duct locationOccupied space branch
Results
- Velocity1,100 FPM
- Recommended limit for this location700 FPM
- StatusExceeds recommended limit — increase duct size
Frequently asked questions
Why do limits vary by location?
Occupied rooms are far more sensitive to airflow noise than a mechanical room or attic, so limits are much stricter there.
What if velocity is too high?
Increase the duct diameter, which lowers velocity for the same CFM and quiets the run.
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.