NPS to DN Converter
Convert NPS to DN and vice versa with common size mapping for ASME and EN projects.
| NPS (in) | DN | Notes |
|---|---|---|
| 1/8 | DN 6 | Nominal size mapping |
| 1/4 | DN 8 | Nominal size mapping |
| 3/8 | DN 10 | Nominal size mapping |
| 1/2 | DN 15 | Nominal size mapping |
| 3/4 | DN 20 | Nominal size mapping |
| 1 | DN 25 | Nominal size mapping |
| 1-1/4 | DN 32 | Nominal size mapping |
| 1-1/2 | DN 40 | Nominal size mapping |
| 2 | DN 50 | Nominal size mapping |
| 2-1/2 | DN 65 | Nominal size mapping |
| 3 | DN 80 | Nominal size mapping |
| 4 | DN 100 | Nominal size mapping |
| 5 | DN 125 | Nominal size mapping |
| 6 | DN 150 | Nominal size mapping |
| 8 | DN 200 | Nominal size mapping |
| 10 | DN 250 | Nominal size mapping |
| 12 | DN 300 | Nominal size mapping |
| 14 | DN 350 | Nominal size mapping |
| 16 | DN 400 | Nominal size mapping |
| 18 | DN 450 | Nominal size mapping |
| 20 | DN 500 | Nominal size mapping |
| 24 | DN 600 | Nominal size mapping |
| 30 | DN 750 | Nominal size mapping |
| 36 | DN 900 | Nominal size mapping |
Quick Reference
1/2 → DN 152 → DN 504 → DN 1006 → DN 1508 → DN 20012 → DN 300
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What is NPS?
NPS (Nominal Pipe Size) is a North American size designation in inches, but it is not the exact outside diameter.
What is DN?
DN (Nominal Diameter) is the metric designation used in ISO/EN standards. It is a nominal size, not an exact diameter.
Frequently Asked Questions
Is DN the exact pipe diameter in mm?
No. DN is a nominal size. Actual OD varies by standard.
Are NPS and DN always 1:1?
They are standardized mappings, but always verify OD and wall thickness from the applicable standard.
Which standard should I follow?
Use ASME B36.10M/B36.19M for NPS and EN/ISO tables for DN projects.
Disclaimer: Reference only. Confirm dimensions with the specified standard and manufacturer drawings.