Size converter: DN ↔ inch ↔ outside diameter
| DN | Inch (NPS) | OD mm | OD in |
|---|---|---|---|
| DN15 | 1/2" | 21.3 | 0.839 |
| DN20 | 3/4" | 26.7 | 1.051 |
| DN25 | 1" | 33.4 | 1.315 |
| DN32 | 1-1/4" | 42.2 | 1.661 |
| DN40 | 1-1/2" | 48.3 | 1.902 |
| DN50 | 2" | 60.3 | 2.374 |
| DN65 | 2-1/2" | 73.0 | 2.874 |
| DN80 | 3" | 88.9 | 3.500 |
| DN100 | 4" | 114.3 | 4.500 |
| DN125 | 5" | 141.3 | 5.563 |
| DN150 | 6" | 168.3 | 6.626 |
| DN200 | 8" | 219.1 | 8.626 |
| DN250 | 10" | 273.0 | 10.748 |
| DN300 | 12" | 323.8 | 12.748 |
| DN350 | 14" | 355.6 | 14.000 |
| DN400 | 16" | 406.4 | 16.000 |
| DN450 | 18" | 457.0 | 17.992 |
| DN500 | 20" | 508.0 | 20.000 |
| DN600 | 24" | 610.0 | 24.016 |
Outside diameters per ASME B36.10 steel pipe. Note: some European systems use 76.1 mm for 2-1/2" instead of 73.0 mm, so confirm the matching grooved coupling size.