Rectangular Duct Aspect Ratio Calculator

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Aspect Ratio of a duct is the Ratio of Width to Height or Height to Width (longer side to shorter side) of a Rectangular Duct.

The closer the Aspect Ratio of a duct to 1, or the “squarer” the duct is, the more the savings can be achieved, because the Total Duct (Metal Sheet) Surface Area can be minimized.

The Total Duct Surface area for a square duct whose aspect ratio, AR = 1,

The % extra material (& subsequently cost) of a rectangular duct comparing to a square duct whose aspect ratio, AR = 1, can be represented with simple formula below:

A downloadable Excel File for Rectangular Duct Surface Area based on Aspect Ratio and the % Difference in Material is available below.

Duct Aspect Ratio Calculator (Excel)