NPS to DN Conversion Chart
| NPS | DN | Outside Diameter | Outside Diameter (Metric) |
|---|---|---|---|
| NPS 2 | 50 | 2.375 in | 60.33 mm |
| NPS 3 | 80 | 3.5 in | 88.9 mm |
| NPS 4 | 100 | 4.5 in | 114.3 mm |
| NPS 6 | 150 | 6.625 in | 168.28 mm |
| NPS 8 | 200 | 8.625 in | 219.07 mm |
| NPS 10 | 250 | 10.75 in | 273.05 mm |
| NPS 12 | 300 | 12.75 in | 323.85 mm |
NPS to DN Conversion
NPS means Nominal Pipe Size, while DN is the metric nominal diameter designation used for pipe sizes. NPS and DN are standardized size designations and are not direct measurements of the actual pipe outside diameter.
For example, NPS 2 corresponds to DN 50. The standard outside diameter for NPS 2 steel pipe is 2.375 inches, or 60.33 mm.
Use the NPS links in the table to view the available Schedule 40 and Schedule 80 dimensions for each pipe size.
Reference standard: ASME B36.10-2022.
Related Pipe References
FAQ
What is the DN equivalent of NPS 2?
NPS 2 corresponds to DN 50.
Is DN the actual pipe diameter?
No. DN is a nominal metric designation. The actual outside diameter depends on the standardized pipe size.
Does NPS equal the actual outside diameter?
No. NPS is a nominal size designation. For example, NPS 2 has a standard outside diameter of 2.375 inches.
What standard does this conversion reference use?
The pipe size relationships shown here reference ASME B36.10-2022.