1-1/4
For 1-1/4, thread standard is NPT; threads per inch (tpi) is 11 1/2; thread pitch (mm) is 2.2087; major (outside) diameter (mm) is 42.1640; thread angle (degrees) is 60, recorded from its source on 2026-08-12.
- Thread standard
- NPT our reading
- Nominal size
- 1-1/4
- Threads per inch (TPI)
- 11 1/2
- Thread pitch (mm)
- 2.2087
- Major (outside) diameter (mm)
- 42.1640 verified
- Thread angle (degrees)
- 60 our reading
- Governing standard
- ASME B1.20.1 our reading
Values marked our reading are our classification of what the source says — the source does not print them in those words. The quote below is the evidence for each one; judge it yourself.
What the source says
1.660 | 42.1640 |
— en.wikipedia.org, retrieved 2026-08-12
Source
- en.wikipedia.orghttps://en.wikipedia.org/wiki/National_pipe_thread