Duct Velocity Calculator
Who it's for: HVAC technicians, duct designers, and installers.
Calculator Inputs
Quick Summary
- Built for: HVAC technicians, duct designers, and installers.
- Key outputs: Duct area (sq ft), Velocity (fpm), and more.
- Use this page for early planning estimates before final code and manufacturer verification.
Inputs
- Airflow (CFM)
- Duct shape
- Round diameter or rectangular width and height
Outputs
- Duct area (sq ft)
- Velocity (fpm)
- Common velocity range note
How this calculator estimates results
- Calculates cross-sectional area from round or rectangular dimensions.
- Computes velocity using velocity = airflow / area.
- Displays non-binding common range guidance for quick interpretation.
Cross-check assumptions with Duct Size Calculator for a more complete planning workflow.
Common ranges and tips
- Verify dimensions at actual internal duct size, not nominal labels.
- Higher velocity can increase noise and pressure loss.
- Use with friction/equivalent length checks for better planning.
Related Calculators
FAQ
Different shapes change cross-sectional area for the same nominal dimensions, which changes velocity.
A common planning range is roughly 600-900 fpm supply and 400-700 fpm return, but projects vary.
Yes. Higher velocities can increase acoustic issues and pressure penalties.
No. Use this as an estimate and validate with full duct design methods and manufacturer data.
Disclaimer: Use results for planning only. Final design and installation decisions must follow local code and manufacturer documentation.
Back to HVAC hub