NPS (Nominal Pipe Size) is a dimensionless ordinal number used to represent pipe size. A number after it indicates a standard pipe. For example: the outer diameter of steel pipes represented by NPS 6 is uniformly 168.3mm.
DN: Normal Diameter
ASME B36.10/36.19 NPS to DN Conversion Chart
| PIPE NPS | Pipe outside diameter in inches |
PIpe outside diameter in mm |
NPS to DN conversion |
|---|---|---|---|
| 1/8 | 0.404 | 10.26 | 6 |
| 1/4 | 0.54 | 13.72 | 8 |
| 3/8 | 0.675 | 17.15 | 10 |
| 1/2 | 0.84 | 21.34 | 15 |
| ¾ | 1.05 | 26.67 | 20 |
| 1 | 1.315 | 33.40 | 25 |
| 1 ¼ | 1.66 | 42.16 | 32 |
| 1 ½ | 1.9 | 48.26 | 40 |
| 2 | 2.375 | 60.33 | 50 |
| 2 ½ | 2.875 | 73.03 | 65 |
| 3 | 3.5 | 88.90 | 80 |
| 3 ½ | 4 | 101.60 | 90 |
| 4 | 4.5 | 114.30 | 100 |
| 4 ½ | 5 | 127.00 | 115 |
| 5 | 5.563 | 141.30 | 125 |
| 6 | 6.625 | 168.28 | 150 |
| 7 | 7.625 | 193.68 | — |
| 8 | 8.625 | 219.08 | 200 |
| 10 | 10.75 | 273.05 | 250 |
| 12 | 12.75 | 323.85 | 300 |
| 14 | 14 | 355.60 | 350 |
| 16 | 16 | 406.40 | 400 |
| 18 | 18 | 457.20 | 450 |
| 20 | 20 | 508.00 | 500 |
| 22 | 22 | 558.80 | 550 |
| 24 | 24 | 609.60 | 600 |
| 26 | 26 | 660.40 | 650 |
| 28 | 28 | 711.20 | 700 |
| 30 | 30 | 762.00 | 750 |
| 32 | 32 | 812.80 | 800 |
| 34 | 34 | 863.60 | 850 |
| 36 | 36 | 914.40 | 900 |
| 38 | 38 | 965.20 | 950 |
| 40 | 40 | 1016.00 | 1000 |
| 42 | 42 | 1066.80 | 1050 |
| 44 | 44 | 1117.60 | 1100 |
| 46 | 46 | 1168.40 | 1150 |
| 48 | 48 | 1219.20 | 120 |
