2-1/2
For 2-1/2, thread standard is BSP; threads per inch (tpi) is 11; thread pitch (mm) is 2.309; major (outside) diameter (mm) is 75.184; minor diameter (mm) is 72.226, recorded from its source on 2026-08-12.
- Thread standard
- BSP our reading
- Nominal size
- 2-1/2
- Threads per inch (TPI)
- 11 verified
- Thread pitch (mm)
- 2.309 verified
- Major (outside) diameter (mm)
- 75.184 verified
- Minor diameter (mm)
- 72.226 verified
- Thread angle (degrees)
- 55 our reading
- Governing standard
- ISO 228-1 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
2½ | 11 | 2.309 | 1.479 | 75.184 | 73.705 | 72.226 |
— amesweb.info, retrieved 2026-08-12
Source
- amesweb.infohttps://amesweb.info/Screws/BSP-Thread-Chart.aspx