Air Duct Velocity Calculator

An air duct velocity calculator helps you calculate how fast air is moving through your ductwork based on shape, size, and flow rate.

Furthermore, this allows you to check if your system stays within optimal velocity ranges.

You divide the airflow rate by the cross-sectional area of the duct.

This is the standard method for calculating air velocity in ducts.

Yes, this air velocity calculator supports both circular and rectangular ducts.

As a result, you can model a wide range of HVAC systems accurately.

The calculator supports both metric (L/s, m/s) and imperial (CFM, FPM) systems.

Therefore, this flexibility helps it serve engineers globally.

You'll need to select the duct type, enter the internal diameter (or width and height), and provide the airflow rate.

From there, the calculator handles the rest.

For supply ducts, 600–900 FPM (3–4.5 m/s) is typical, while returns are often lower.

However, always refer to local standards and project-specific requirements.

While it doesn't directly choose a duct size, it helps you see if your chosen size produces a suitable velocity.

Therefore, it's useful for both sizing and verification.

Also, you can check out our Duct Size Calculator and Ductulator to help with sizing ductwork.

Yes, this works well as a residential air duct sizer and velocity calculator.

Also, it's used in commercial applications.

A duct size calculator helps you choose the dimensions based on flow and velocity limits.

In contrast, this air velocity calculator checks the velocity of a duct you've already selected.

Yes, the same air velocity calculation logic is built into h2x's full mechanical and plumbing design platform.

That way, your calculator results align with full project designs.