Rectangular Duct Aspect Ratio Calculator

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.

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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.

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

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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)