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Airflow & Duct Size Calculator

Calculate circular duct diameter from airflow and target velocity.

Transparent calculationFormula and assumptions shown
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Enter your values

02

Your result

Duct diameter504.626504mm
FORMULA USEDD = √(4Q / πv)
METHOD

How this calculation works

The calculator substitutes your values into the stated engineering relationship and evaluates the result using the displayed units. Change any input to recalculate instantly.

Important

This is an idealised engineering calculation. Confirm material properties, loading conditions and applicable design factors before specification or construction.