Dr-Fix-It! Equivalent HVAC Duct Sizes By CFMA table showing typical minimum rectangular and round HVAC duct dimensions required to deliver specific airflows. |
|
Cubic Feet per Minute |
Rectangular Duct Sizes Side Dimensions in Inches |
Round Duct Sizes Diameter in Inches |
100 | 3 X 4 | 4 |
200 | 3 X 7 4 X 5 |
5 |
300 | 4 X 7 5 X 6 |
6 |
400 | 4 X 9 5 X 7 6 X 6 |
7 |
500 | 6 X 7 | 8 |
750 | 5 X 12 6 X 10 7 X 8 |
9 |
1000 | 7 X 10 8 X 9 |
10 |
1250 | 8 X 10 9 X 9 |
10 |
1500 | 8 X 12 10 X 10 |
12 |
1750 | 8 X 14 9 X 12 10 X 11 |
12 |
2000 | 8 X 15 10 X 12 |
12 |
2500 | 10 X 14 12 X 12 |
14 |
3000 | 12 X 14 | 14 |
3500 | 12 X 15 | 15 |
4000 | 10 X 22 14 X 15 |
16 |
4500 | 12 X 19 14 X 16 |
17 |
5000 | 10 X 25 12 X 20 15 X 16 |
17 |
6000 | 14 X 20 15 X 18 |
19 |
7000 | 12 X 26 16 X 20 |
20 |
8000 | 12 X 30 14 X 25 |
21 |
9000 | 12 X 34 15 X 25 |
22 |
10000 | 12 X 36 16 X 25 20 X 20 |
23 |
12500 | 12 X 45 16 X 30 20 X 24 |
24 |
15000 | 16 X 36 18 X 30 23 X 25 |
26 |
17500 | 16 X 40 20 X 32 25 X 25 |
28 |
20000 | 16 X 45 20 X 35 25 X 28 |
30 |
25000 | 16 X 55 20 X 43 25 X 38 |
32 |
30000 | 20 X 50 30 X 32 |
34 |
35000 | 20 X 55 30 X 35 |
36 |
40000 | 25 X 48 30 X 40 |
38 |
45000 | 25 X 25 32 X 40 |
40 |
50000 | 32 X 45 35 X 40 |
42 |