Pipe schedule chart — ASME B36.10M & B36.19M
Outside diameter and wall thickness (mm) for seamless and welded steel pipe to ASME B36.10M (carbon & alloy) and ASME B36.19M (stainless, "S" schedules). Tap Show inches to convert.
| NPS | DN | OD | Sch 5S | Sch 10S | Sch 10 | Sch 20 | Sch 30 | STD | Sch 40 | Sch 60 | XS | Sch 80 | Sch 100 | Sch 120 | Sch 140 | Sch 160 | XXS |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1/8" | 6 | 10.30 | – | 1.24 | – | – | – | 1.73 | 1.73 | – | 2.41 | 2.41 | – | – | – | – | – |
| 1/4" | 8 | 13.70 | – | 1.65 | – | – | – | 2.24 | 2.24 | – | 3.02 | 3.02 | – | – | – | – | – |
| 3/8" | 10 | 17.10 | – | 1.65 | – | – | – | 2.31 | 2.31 | – | 3.20 | 3.20 | – | – | – | – | – |
| 1/2" | 15 | 21.30 | 1.65 | 2.11 | – | – | – | 2.77 | 2.77 | – | 3.73 | 3.73 | – | – | – | 4.78 | 7.47 |
| 3/4" | 20 | 26.70 | 1.65 | 2.11 | – | – | – | 2.87 | 2.87 | – | 3.91 | 3.91 | – | – | – | 5.56 | 7.82 |
| 1" | 25 | 33.40 | 1.65 | 2.77 | – | – | – | 3.38 | 3.38 | – | 4.55 | 4.55 | – | – | – | 6.35 | 9.09 |
| 1-1/4" | 32 | 42.20 | 1.65 | 2.77 | – | – | – | 3.56 | 3.56 | – | 4.85 | 4.85 | – | – | – | 6.35 | 9.70 |
| 1-1/2" | 40 | 48.30 | 1.65 | 2.77 | – | – | – | 3.68 | 3.68 | – | 5.08 | 5.08 | – | – | – | 7.14 | 10.15 |
| 2" | 50 | 60.30 | 1.65 | 2.77 | – | – | – | 3.91 | 3.91 | – | 5.54 | 5.54 | – | – | – | 8.74 | 11.07 |
| 2-1/2" | 65 | 73.00 | 2.11 | 3.05 | – | – | – | 5.16 | 5.16 | – | 7.01 | 7.01 | – | – | – | 9.53 | 14.02 |
| 3" | 80 | 88.90 | 2.11 | 3.05 | – | – | – | 5.49 | 5.49 | – | 7.62 | 7.62 | – | – | – | 11.13 | 15.24 |
| 3-1/2" | 90 | 101.60 | 2.11 | 3.05 | – | – | – | 5.74 | 5.74 | – | 8.08 | 8.08 | – | – | – | – | – |
| 4" | 100 | 114.30 | 2.11 | 3.05 | – | – | – | 6.02 | 6.02 | – | 8.56 | 8.56 | – | 11.13 | – | 13.49 | 17.12 |
| 5" | 125 | 141.30 | 2.77 | 3.40 | – | – | – | 6.55 | 6.55 | – | 9.53 | 9.53 | – | 12.70 | – | 15.88 | 19.05 |
| 6" | 150 | 168.30 | 2.77 | 3.40 | – | – | – | 7.11 | 7.11 | – | 10.97 | 10.97 | – | 14.27 | – | 18.26 | 21.95 |
| 8" | 200 | 219.10 | 2.77 | 3.76 | – | 6.35 | 7.04 | 8.18 | 8.18 | 10.31 | 12.70 | 12.70 | 15.09 | 18.26 | 20.62 | 23.01 | 22.23 |
| 10" | 250 | 273.10 | 3.40 | 4.19 | – | 6.35 | 7.80 | 9.27 | 9.27 | 12.70 | 12.70 | 15.09 | 18.26 | 21.44 | 25.40 | 28.58 | 25.40 |
| 12" | 300 | 323.90 | 3.96 | 4.57 | – | 6.35 | 8.38 | 9.53 | 10.31 | 14.27 | 12.70 | 17.48 | 21.44 | 25.40 | 28.58 | 33.32 | 25.40 |
| 14" | 350 | 355.60 | 3.96 | 4.78 | 6.35 | 7.92 | 9.53 | 9.53 | 11.13 | 15.09 | 12.70 | 19.05 | 23.83 | 27.79 | 31.75 | 35.71 | – |
| 16" | 400 | 406.40 | 4.19 | 4.78 | 6.35 | 7.92 | 9.53 | 9.53 | 12.70 | 16.66 | 12.70 | 21.44 | 26.19 | 30.96 | 36.53 | 40.49 | – |
| 18" | 450 | 457.00 | 4.19 | 4.78 | 6.35 | 7.92 | 11.13 | 9.53 | 14.27 | 19.05 | 12.70 | 23.83 | 29.36 | 34.93 | 39.67 | 45.24 | – |
| 20" | 500 | 508.00 | 4.78 | 5.54 | 6.35 | 9.53 | 12.70 | 9.53 | 15.09 | 20.62 | 12.70 | 26.19 | 32.54 | 38.10 | 44.45 | 50.01 | – |
| 24" | 600 | 610.00 | 5.54 | 6.35 | 6.35 | 9.53 | 14.27 | 9.53 | 17.48 | 24.61 | 12.70 | 30.96 | 38.89 | 46.02 | 52.37 | 59.54 | – |
| 26" | 650 | 660.00 | – | – | – | – | – | 9.53 | – | – | 12.70 | – | – | – | – | – | – |
| 28" | 700 | 711.00 | – | – | – | – | – | 9.53 | – | – | 12.70 | – | – | – | – | – | – |
| 30" | 750 | 762.00 | – | – | – | – | – | 9.53 | – | – | 12.70 | – | – | – | – | – | – |
| 32" | 800 | 813.00 | – | – | – | – | – | 9.53 | – | – | 12.70 | – | – | – | – | – | – |
| 34" | 850 | 864.00 | – | – | – | – | – | 9.53 | – | – | 12.70 | – | – | – | – | – | – |
| 36" | 900 | 914.00 | – | – | – | – | – | 9.53 | – | – | 12.70 | – | – | – | – | – | – |
| 42" | 1050 | 1067.00 | – | – | – | – | – | 9.53 | – | – | 12.70 | – | – | – | – | – | – |
| 48" | 1200 | 1219.00 | – | – | – | – | – | 9.53 | – | – | 12.70 | – | – | – | – | – | – |
STD = standard weight, XS = extra strong, XXS = double extra strong. "–" means the schedule is not listed for that size. Schedules 40S/80S for stainless equal STD/XS up to NPS 10; at NPS 12 they are 9.53 mm and 12.70 mm.
How to read a pipe schedule
Nominal pipe size (NPS) is a name, not a measurement. From NPS ⅛ to 12 the outside diameter is slightly larger than the nominal size; from NPS 14 upward the OD equals the nominal size in inches. For any given NPS the OD stays fixed — a higher schedule adds wall thickness inward, reducing the bore. That is why a Sch 160 and a Sch 40 pipe of the same NPS fit the same flange.
Frequently asked questions
What is the difference between Schedule 40 and STD?
Up to NPS 10 they are identical. From NPS 12 upward STD stays at 9.53 mm (0.375 in) wall while Schedule 40 keeps increasing.
What is the OD of a 2 inch Schedule 40 pipe?
A 2 inch (DN 50) pipe has an OD of 60.3 mm in every schedule. Schedule 40 wall thickness is 3.91 mm.
What does the S in 10S or 40S mean?
The S suffix marks stainless steel schedules from ASME B36.19M. They share the same OD as carbon steel pipe but some walls differ.
Is pipe OD the same as nominal size?
Only from NPS 14 and above. Below that, OD is larger than the nominal size, e.g. a 1 inch pipe has an OD of 33.4 mm.
Last updated 2026-11-02