Nominal diameter to nominal pipe size
Type a value in DN to get it in NPS instantly.
1NPS
That's about the same as a 1" gas line.
Convert the other way: NPS to DN
What it means
How big is that pipe?
Steel pipe to ASME B36.10 / ISO 6708. The outside diameter is the same for every schedule; the wall, and so the bore, changes. Copper tube and PVC have their own sizes.
The math
How to convert DN to NPS
Pipe sizes are a table: NPS 2 = DN 50 = 60.3 mm (2.375 in) OD, NPS 4 = DN 100 = 114.3 mm. From NPS 14 the OD equals the NPS in inches.
Example: DN 25 DN = 1 NPS.
Every unit
That pipe in every system
Tables
DN to NPS conversion table
| DN | NPS |
|---|---|
| DN 6 DN | 1/8 NPS |
| DN 8 DN | 1/4 NPS |
| DN 10 DN | 3/8 NPS |
| DN 15 DN | 1/2 NPS |
| DN 20 DN | 3/4 NPS |
| DN 25 DN | 1 NPS |
| DN 32 DN | 1 1/4 NPS |
| DN 40 DN | 1 1/2 NPS |
| DN 50 DN | 2 NPS |
| DN 65 DN | 2 1/2 NPS |
| DN 80 DN | 3 NPS |
| DN 100 DN | 4 NPS |
| DN 125 DN | 5 NPS |
| DN 150 DN | 6 NPS |
| DN 200 DN | 8 NPS |
| DN 250 DN | 10 NPS |
| DN 300 DN | 12 NPS |
| DN 350 DN | 14 NPS |
| DN 400 DN | 16 NPS |
| DN 450 DN | 18 NPS |
| DN 500 DN | 20 NPS |
| DN 600 DN | 24 NPS |
NPS to DN conversion table
| NPS | DN |
|---|---|
| 1/8 NPS | DN 6 DN |
| 1/4 NPS | DN 8 DN |
| 3/8 NPS | DN 10 DN |
| 1/2 NPS | DN 15 DN |
| 3/4 NPS | DN 20 DN |
| 1 NPS | DN 25 DN |
| 1 1/4 NPS | DN 32 DN |
| 1 1/2 NPS | DN 40 DN |
| 2 NPS | DN 50 DN |
| 2 1/2 NPS | DN 65 DN |
| 3 NPS | DN 80 DN |
| 4 NPS | DN 100 DN |
| 5 NPS | DN 125 DN |
| 6 NPS | DN 150 DN |
| 8 NPS | DN 200 DN |
| 10 NPS | DN 250 DN |
| 12 NPS | DN 300 DN |
| 14 NPS | DN 350 DN |
| 16 NPS | DN 400 DN |
| 18 NPS | DN 450 DN |
| 20 NPS | DN 500 DN |
| 24 NPS | DN 600 DN |
Quick answers
Quick answers
- How many NPS is DN 10 DN?
- DN 10 DN is 3/8 NPS.
- How many NPS is DN 25 DN?
- DN 25 DN is 1 NPS.
The units
About these units
Nominal diameter (DN)
The metric nominal size: DN 15, 25, 50…
Nominal pipe size (NPS)
The US nominal size in inches: ½, 1, 2…
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