DN to NPS Pipe Size Chart
DN to NPS pipe size chart from DN6 to DN600: inch nominal sizes with European and ASME outside diameters in mm. DN and NPS are not actual diameters.
For preliminary reference and dimensional comparison. Tolerances, pressure capacity and joint safety are not assessed. Confirm against the applicable standard before manufacture or final selection.
Dimension drawing and symbols
- D
- European outside diameter mm
DN and NPS are nominal sizes, not diameters. D is the actual outside diameter in both series.
Columns
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Visible rows: 22
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| Outside diameter, mm | |||
|---|---|---|---|
| DN | NPS | DEuropean | DASME |
| DN6 | 1/8 | 10.2 | 10.3 |
| DN8 | 1/4 | 13.5 | 13.7 |
| DN10 | 3/8 | 17.2 | 17.1 |
| DN15 | 1/2 | 21.3 | 21.3 |
| DN20 | 3/4 | 26.9 | 26.7 |
| DN25 | 1 | 33.7 | 33.4 |
| DN32 | 1 1/4 | 42.4 | 42.2 |
| DN40 | 1 1/2 | 48.3 | 48.3 |
| DN50 | 2 | 60.3 | 60.3 |
| DN65 | 2 1/2 | 76.1 | 73.0 |
| DN80 | 3 | 88.9 | 88.9 |
| DN100 | 4 | 114.3 | 114.3 |
| DN125 | 5 | 139.7 | 141.3 |
| DN150 | 6 | 168.3 | 168.3 |
| DN200 | 8 | 219.1 | 219.1 |
| DN250 | 10 | 273.0 | 273.0 |
| DN300 | 12 | 323.9 | 323.8 |
| DN350 | 14 | 355.6 | 355.6 |
| DN400 | 16 | 406.4 | 406.4 |
| DN450 | 18 | 457.0 | 457.0 |
| DN500 | 20 | 508.0 | 508.0 |
| DN600 | 24 | 610.0 | 610.0 |
Quick answers
- DN15 corresponds to NPS 1/2. European outside diameter 21.3 mm, ASME outside diameter 21.3 mm. View in table
- DN20 corresponds to NPS 3/4. European outside diameter 26.9 mm, ASME outside diameter 26.7 mm. View in table
- DN25 corresponds to NPS 1. European outside diameter 33.7 mm, ASME outside diameter 33.4 mm. View in table
- DN50 corresponds to NPS 2. European outside diameter 60.3 mm, ASME outside diameter 60.3 mm. View in table
- DN80 corresponds to NPS 3. European outside diameter 88.9 mm, ASME outside diameter 88.9 mm. View in table
- DN100 corresponds to NPS 4. European outside diameter 114.3 mm, ASME outside diameter 114.3 mm. View in table
- DN150 corresponds to NPS 6. European outside diameter 168.3 mm, ASME outside diameter 168.3 mm. View in table
- DN200 corresponds to NPS 8. European outside diameter 219.1 mm, ASME outside diameter 219.1 mm. View in table
Conditions and notes
European column uses the general purpose outside diameter series of EN 10220:2002 and ISO 4200:1991. ASME column uses nominal dimensions referenced to B36.10M:2018.
- DN and NPS are nominal labels and are not converted as lengths. Inside diameter also requires wall thickness.
- European and ASME series are not interchangeable. DN65 is shown as 76.1 mm and 73 mm. EN 10255 is a separate series and uses 165.1 mm for DN150.
- Published nominal dimensions use their own rounding conventions. Confirm the contractual edition and tolerances.
- ASME B36.10:2022 changed SI outside diameter rounding. This table uses the 2018 series. Confirm the contractual standard before switching editions or dimension series.
- CSV download is unavailable because the sources do not establish permission for reuse.
Common pipe sizes from DN6 to DN600. European and ASME outside diameters are shown separately. DN and NPS are nominal designations.
Sources
This table is for preliminary reference. Check the applicable standard and product conditions before use.
- Source 1. Product overview 2013, referencing EN 10220. Accessed: 2026-10-16
- Source 2. Undated numerical table. The referenced edition is stated in the conditions.. Accessed: 2026-10-16
- Source 3. Undated numerical table. The referenced edition is stated in the conditions.. Accessed: 2026-10-16
- Source 4. Undated catalogue referencing ASME B36.10. Accessed: 2026-10-16
- Source 5. Undated numerical table. The referenced edition is stated in the conditions.. Accessed: 2026-10-16
- Source 6. Undated web table referencing ASME B36.10M. Accessed: 2026-10-16
Data version: 2026-10-16