Circular Ducts - Dimensions

Sizes of circular ventilation air ducts

Circular galvanized steel duct

Circular Ducts Dimensions - Metric Units

Common circular ductwork sizes used in air handling ventilation systems:

Nominal Diameter
(mm)
Outside Diameter
(mm)
Inside Diameter
(mm)
63 63 - 63.5 61.8 - 62.3
80 80 - 80.5 78.8 - 79.3
100 100 - 100.5 98.8 - 99.3
125 125 - 125.5 123.8 - 124.3
160 160 - 160.6 158.7 - 159.3
200 200 - 200.7 198.6 - 199.3
250 250 - 250.8 248.5 - 249.3
315 315 - 315.9 313.4 - 314.3
400 400 - 401.0 398.3 - 399.3
500 500 - 501.1 498.2 - 499.3
630 630 - 631.2 628.1 - 629.3
800 800 - 801.6 798.0 - 799.3
1000 1000 - 1002.0 997.9 - 999.3
1250 1250 - 1252.5 1247.8 - 1249.3

Circular Galvanized Steel Ducts - Areas and Weights - Imperial Units

Diameter
(inches)
Surface Area
(ft2/ft)
Gage
262422
Weight (lbs/ft)
4 1.05 1.02 1.36 1.59
5 1.31 1.25 1.67 1.95
6 1.57 1.49 1.98 2.32
7 1.83 1.72 2.30 2.69
8 2.09 1.96 2.61 3.06
9 2.36 2.20 2.93 3.42
10 2.62 2.51 3.34 3.91
11 2.88 2.74 3.66 4.28
12 3.14 2.98 3.97 4.64
13 3.40 3.21 4.28 5.01
14 3.67 3.45 4.60 5.38
15 3.93 3.68 4.91 5.75
16 4.19 3.92 5.23 6.12
17 4.45 4.16 5.54 6.48
18 4.72 4.39 5.85 6.85
19 4.98 4.63 6.17 7.22
20 5.24 4.94 6.58 7.70
21 5.50 5.18 6.90 8.07
22 5.75 5.41 7.21 8.44
23 6.02 5.64 7.53 8.80
24 6.28 5.88 7.84 9.17
25 6.54 6.12 8.15 9.54
26 6.80 6.35 8.47 9.91
27 7.07 8.78 10.27 12.47
28 7.33 9.10 10.64 12.92
29 7.59 9.41 11.01 13.36
30 7.85 9.83 11.50 13.95
31 8.11 10.14 11.86 14.40
32 8.38 10.45 12.23 14.84
33 8.65 10.77 12.67 15.29
34 8.91 11.08 12.96 15.75
35 9.17 11.40 13.33 16.18
36 9.43 11.71 13.70 16.63
37 9.69 12.02 14.07 17.07
38 9.95 12.34 14.44 17.52
39 10.21 12.65 14.80 17.97
40 10.47 13.07 15.29 18.55
41 10.73 13.39 15.66 19.00
42 10.99 13.70 16.02 19.45
43 11.26 14.01 16.39 19.89
44 11.52 14.32 16.76 20.34

Related Topics

  • Ventilation - Systems for ventilation and air handling - air change rates, ducts and pressure drops, charts and diagrams and more

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