Calculate Rectangular Duct Equivalent Diameter
Kindly enter the preferred width and height of your duct to calculate the equivalent diameter:
How to Calculate the Equivalent Diameter of a Rectangular Duct
Based on the duct design chapter of the ASHRAE Handbook of Fundamentals, the equivalent diameter of a rectangular duct is calculated using the below formula:
De = 1.3 (ab)0.625 / (a+b)0.25
where,
De = Circular equivalent of rectangular duct for equal length, fluid resistance and airflow (inch or mm)
a = Length one side of duct (inch or mm)
b = Length adjacent side of duct (inch or mm)
Convert Cubic Meter per Hour to Litre per Second
Enter your airflow in CMH (m³/hr) to convert into litre per second (L/s):
Convert Feet per Minute to Meter per Second
Enter your velocity in FPM (ft/min) to convert into meter per second (m/s):