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Knowledge Center / Equivalent Square Inches of Round Duct

 The formula for determining the area of a circle is A = n.r2  Below for your convenience is a quick reference chart listing the equivalent square inches for round duct. 

 

Round Duct Diameter Equivalent Square Inches
3 7.07
4 12.57
5 19.64
6 28.27
7 38.48
8 50.26
9 63.62
10 78.54
12 113.1
14 153.94
16 201.06
18 254.47
20 314.16
22 380.13

 

 

 

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