Converting Round Duct Areas to Square Feet
Duct Diameter,
Inches		 Duct Diameter,
mm		 Area
Ft2		 Area
m2
8
10		 203
254		 0.3491
0.5454		 0.032
0.051
12
14		 305
356		 0.7854
1.069		 0.073
0.099
16
18		 406
457		 1.396
1.767		 0.130
0.290
20
22		 508
559		 2.182
2.640		 0.203
0.245
24
26		 609
660		 3.142
3.687		 2.292
0.342
28
30		 711
762		 4.276
4.900		 0.397
0.455
32
34		 813
864		 5.585
6.305		 0.519
0.586
36
38		 914
965		 7.069
7.786		 0.657
0.732
40
42		 1016
1067		 8.727
9.62		 0.811
0.894
44
46		 1119
1168		 10.56
11.54		 0.981
1.072
48
50		 1219
1270		 12.57
13.67		 1.168
1.270
52
54		 1321
1372		 14.75
15.90		 1.370
1.477
56
58		 1422
1473		 17.10
18.35		 1.586
1.705
60 1524 19.63 1.824
Back to Industry Tables Round Duct Area to Square Feet Calculator