About the Duct Velocity Calculator Online Free Tool

The Duct Velocity Calculator Online Free Tool converts airflow and duct dimensions into duct area and air velocity for rectangular or circular ducts. It is useful for HVAC sizing checks and airflow troubleshooting.

How to Use the Duct Velocity Calculator Online

1. Enter the required inputs in the fields above using the units shown on the labels.
2. Select any mode, shape, or method options so the calculation matches your scenario.
3. Run the calculation and review the result summary in the output panel.
4. Check the units, assumptions, and project requirements before using the result outside preliminary review.

Choosing Options Correctly

Airflow is entered in m^3/h. Rectangular duct dimensions and circular diameter are entered in millimeters, and the shape selector controls which dimension fields are active.

Common Use Cases

• Check air velocity from a known airflow and duct size.
• Compare rectangular and circular duct options.
• Screen whether velocities are reasonable before pressure-loss calculations.

Quick FAQ

What does this calculate?
It converts airflow and duct area into average air velocity.

Does it calculate pressure loss?
No. Use a duct friction or fan static pressure tool for pressure-loss checks.

Why does velocity matter?
High velocity can increase noise and pressure loss; low velocity can make ducts larger and more costly.

What dimensions should I use?
Use the clear internal duct size, not outside dimensions or nominal labels.