Industrial Fans, Blowers & Air Movement Equipment calculator
Inlet/Outlet Velocity Calculator
Use this calculator to estimate air velocity at a fan inlet, outlet, hood, or duct connection. It helps applications engineers connect airflow, area, inlet screens, dampers, guards, transitions, and blockage allowance to a practical velocity number.
What this calculator does
- Estimate effective inlet or outlet air velocity from airflow, opening area, and efficiency or blockage allowance.
- Use it when checking inlet velocity, outlet velocity, duct connection sizing, discharge speed, or dust collection transport assumptions.
- The result estimates inlet or outlet velocity for the selected opening.
Formula used
- Raw inlet or outlet velocity = airflow through opening ÷ inlet or outlet open area
- Effective inlet or outlet velocity = raw velocity × open-area efficiency allowance
Inputs explained
- Airflow through opening: Use design airflow, measured airflow, or fan curve airflow at the operating point.
- Inlet or outlet open area: Use net open area for the inlet, outlet, duct, damper, screen, guard, or transition.
- Open-area efficiency allowance: Account for screens, guards, louvers, dampers, turbulence, blockage, or measurement correction.
How to use the result
- Use it to check duct sizing, outlet velocity, noise risk, hood capture, and dust transport assumptions.
- It depends on accurate net area, airflow measurement, density correction, and flow profile.
Common questions
- What is the inlet/outlet velocity calculator for? It estimates air velocity at a fan inlet, outlet, duct, or connection.
- What information should I enter? Use airflow, net open area, and open-area efficiency allowance.
- What does the result tell me? The result helps evaluate duct sizing, outlet velocity, noise, and capture or transport assumptions.
- When is the result only an estimate? It is only an estimate when airflow, net area, blockage, density, or flow profile changes.
Last reviewed 2026-05-12.