| minal Size | Carbon / Stainless Steel Pipe OD (mm) | BS 1387:1985 OD (mm) | Cu-Ni Pipe - OD (mm) | ASTM B88M copper tube | ||||||||
| DN/OD | Inch (in) | ISO | DIN | BSP | JIS/KS | USA ASTM | Light | Medium/ Heavy | Metric | USA Inch size | Metric OD (mm) | |
| 6 | ||||||||||||
| 8 | ||||||||||||
| 6* | 1/8 | 10.2 | 10.2 | 10.2 | 10.5 | 10.3 | 10 | |||||
| 8* | 1/4 | 13.5 | 13.5 | 13.5 | 13.8 | 13.7 | 13.6 | 13.9 | 12 | |||
| 15 | ||||||||||||
| 10 | 3/8 | 17.2 | 17.2 | 17.2 | 17.3 | 17.1 | 17.1 | 17.4 | 18 | |||
| 15 | 1/2 | 21.3 | 21.3 | 21.3 | 21.7 | 21.3 | 21.4 | 21.7 | 22 | |||
| 20 | 3/4 | 26.9 | 26.9 | 26.9 | 27.2 | 26.7 | 26.9 | 27.2 | 28 | |||
| 25 | 1 | 33.7 | 33.7 | 33.7 | 34 | 33.4 | 33.8 | 34.2 | 30 | 28.24 | 35 | |
| 32 | 1 1/4 | 42.4 | 42.4 | 42.4 | 42.7 | 42.2 | 42.5 | 42.9 | 38 | 34.59 | 42 | |
| 40 | 1 1/2 | 48.3 | 48.3 | 48.3 | 48.6 | 48.3 | 48.4 | 48.8 | 44.5 | 40.94 | ||
| 50 | 2 | 60.3 | 60.3 | 60.3 | 60.5 | 60.3 | 60.2 | 60.8 | 57 | 54.05 | 54 | |
| 65 | 2 1/2 | 76.1 | 76.1 | 76.1 | 76.3 | 73 | 76 | 76.6 | 76.1 | 66.75 | 67 | |
| 80 | 3 | 88.9 | 88.9 | 88.9 | 89.1 | 88.9 | 88.7 | 89.5 | 88.9 | 79.85 | 79 | |
| 90 | 3 1/2 | 101.6 | 101.6 | 101.6 | 101.6 | 101.6 | ||||||
| 100 | 4 | 114.3 | 114.3 | 114.3 | 114.3 | 114.3 | 113.9 | 114.9 | 108 | 106.27 | 105 | |
| 125 | 5 | 139.7 | 139.7 | 139.7 | 139.8 | 141.3 | 140.6 | 133 | 131.67 | 130 | ||
| 150 | 6 | 168.3 | 168.3 | 165.1** | 165.2 | 168.3 | 166.1 | 159 | 157.68 | 156 | ||
| 200 | 8 | 219.1 | 219.1 | 219.1 | 216.3 | 219.1 | 219 | 208.48 | 206 | |||
| 250 | 10 | 273 | 273 | 273 | 267.4 | 273 | 267 | 260.5 | 257 | |||
| 300 | 12 | 323.9 | 323.9 | 323.9 | 318.5 | 323.8 | 323.8 | 312.11 | 308 | |||
| 350 | 14 | 355.6 | 355.6 | 355.6 | 355.6 | 355.6 | 368 | 363.72 | ||||
| 400 | 16 | 406.4 | 406.4 | 406.4 | 406.4 | 406.4 | 419 | 414.52 | ||||
| 450 | 18 | 457 | 457 | 457 | 457 | 457.2 | 457.2 | 465.32 | ||||
| 500 | 20 | 508 | 508 | 508 | 508 | 508 | 508 | 516.94 | ||||
| JIS = Japanese Industrial Standard | KS = Korean standard |
| **Depending upon the standard number, this may also be 168.3 mm | *Not in ISO 6708 |
|
ISO 6708
1. DN: An alphanumeric designation of size for components of a pipework system, which is used for reference purposes. It comprises the letters DN followed by a dimensionless whole number which is indirectly related to the physical size, in millimetres, of the bore or outside diameter of the end connections. |
2. The number following the letters DN does not represent a measurable value and should not be used for calculation purposes except where specified in the relevant standard.
3. In those standards which use the DN designation system, any relationship between DN and component dimensions should be given, e.g. DN/OD or DN/ID. |
US 5601 
BR 5086 
MY 3868 
IN 2024 
SG 1801 
CN 1762 
VN 1433 
AR 858 
