Round duct air velocity calculator
Calculate average velocity from airflow and diameter.
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Your measurements
Enter your project values. Your estimate updates as you type.
View your estimateExample values are a starting point. Check product yields and specifications before ordering.
YOUR ESTIMATE
Average air velocity
1.965m/s
Calculated from your measurements.
How it's calculated
Velocity (m/s) = airflow (m³/h) ÷ 3600 ÷ [π × (diameter ÷ 2)²].
Calculations use consistent units for your selected measurements. Whole purchase quantities are rounded up.
What this estimate includes
Assumes a full circular cross-section. It does not predict noise, friction loss or balanced branch flows.
Quantity and arithmetic estimates only. Use project specifications for installation and design requirements.
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