Pipe Schedule Chart (ASME B36.10M)
Pick a pipe size and schedule to get the outside diameter, wall thickness, inside diameter and flow area, with the full ASME B36.10M schedule table.
Wall thickness (mm) by schedule, ASME B36.10M
| NPS | OD (mm) | Sch 40 | Sch 80 | Sch 160 | STD | XS | XXS |
|---|---|---|---|---|---|---|---|
| 1/8" | 10.3 | 1.73 | 2.41 | 1.73 | 2.41 | ||
| 1/4" | 13.7 | 2.24 | 3.02 | 2.24 | 3.02 | ||
| 3/8" | 17.1 | 2.31 | 3.20 | 2.31 | 3.20 | ||
| 1/2" | 21.3 | 2.77 | 3.73 | 4.78 | 2.77 | 3.73 | 7.47 |
| 3/4" | 26.7 | 2.87 | 3.91 | 5.56 | 2.87 | 3.91 | 7.82 |
| 1" | 33.4 | 3.38 | 4.55 | 6.35 | 3.38 | 4.55 | 9.09 |
| 1 1/4" | 42.2 | 3.56 | 4.85 | 6.35 | 3.56 | 4.85 | 9.70 |
| 1 1/2" | 48.3 | 3.68 | 5.08 | 7.14 | 3.68 | 5.08 | 10.15 |
| 2" | 60.3 | 3.91 | 5.54 | 8.74 | 3.91 | 5.54 | 11.07 |
| 2 1/2" | 73.0 | 5.16 | 7.01 | 9.53 | 5.16 | 7.01 | 14.02 |
| 3" | 88.9 | 5.49 | 7.62 | 11.13 | 5.49 | 7.62 | 15.24 |
| 4" | 114.3 | 6.02 | 8.56 | 13.49 | 6.02 | 8.56 | 17.12 |
| 6" | 168.3 | 7.11 | 10.97 | 18.26 | 7.11 | 10.97 | 21.95 |
| 8" | 219.1 | 8.18 | 12.70 | 23.01 | 8.18 | 12.70 | 22.23 |
| 10" | 273.1 | 9.27 | 15.09 | 28.58 | 9.27 | 12.70 | 25.40 |
| 12" | 323.8 | 10.31 | 17.48 | 33.32 | 9.53 | 12.70 | 25.40 |
| 14" | 355.6 | 11.13 | 19.05 | 35.71 | 9.53 | 12.70 | |
| 16" | 406.4 | 12.70 | 21.44 | 40.49 | 9.53 | 12.70 | |
| 18" | 457.2 | 14.27 | 23.83 | 45.24 | 9.53 | 12.70 | |
| 20" | 508.0 | 15.09 | 26.19 | 50.01 | 9.53 | 12.70 | |
| 24" | 609.6 | 17.48 | 30.96 | 59.54 | 9.53 | 12.70 |
Pipe Size Basics
The OD of a given NPS is fixed; a higher schedule makes the wall thicker and the bore smaller.
Up to NPS 8, STD equals Sch 40 and XS equals Sch 80. From NPS 10 (XS) and NPS 12 (STD) upwards they differ. Stainless pipe schedules with an S suffix (ASME B36.19M) are not covered here.
Worked example
4" Sch 40: OD 114.3 mm, wall 6.02 mm, so ID = 114.3 − 12.04 = 102.26 mm.
Frequently Asked Questions
What is the ID of a 2" Sch 40 pipe?
60.3 − 2 × 3.91 = 52.5 mm.
Is Sch 40 the same as STD?
Yes up to NPS 10. From NPS 12 STD has a 9.53 mm wall, thinner than Sch 40.
What is the difference between NPS and DN?
NPS is the North American size in inches, DN the metric designation; for example NPS 4 = DN 100.
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