1
For 1, thread standard is BSP; threads per inch (tpi) is 11; thread pitch (mm) is 2.309; major (outside) diameter (mm) is 33.249; minor diameter (mm) is 30.291, recorded from its source on 2026-08-12.
- Thread standard
- BSP our reading
- Nominal size
- 1 verified
- Threads per inch (TPI)
- 11 verified
- Thread pitch (mm)
- 2.309 verified
- Major (outside) diameter (mm)
- 33.249 verified
- Minor diameter (mm)
- 30.291 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
1 | 11 | 2.309 | 1.479 | 33.249 | 31.770 | 30.291 |
— amesweb.info, retrieved 2026-08-12
Sources disagree
More than one authority states this, and they do not state the same thing. Both are reproduced with the source each came from — deciding between them is yours, not ours.
Major (outside) diameter (mm)
amesweb.info says major (outside) diameter (mm) is 33.249, as of 2026-08-12.
1 | 11 | 2.309 | 1.479 | 33.249 | 31.770 | 30.291 |
https://amesweb.info/Screws/BSP-Thread-Chart.aspx
geminivalve.com says major (outside) diameter (mm) is 33.249, as of 2026-08-12.
1 | 11 | 0.0909 | 2.309 | 1.309 | 33.249 | 1.1926 | 30.292 | 0.4091 | 10.391
https://www.geminivalve.com/bsp-thread-vs-npt-fitting/
htsspares.com says major (outside) diameter (mm) is 33.25, as of 2026-08-12.
1 Inch BSP | 33.25 mm / 1-1/4" | 11
https://www.htsspares.com/blog/how-to/how-to-measure-your-bsp-fittings
Minor diameter (mm)
amesweb.info says minor diameter (mm) is 30.291, as of 2026-08-12.
1 | 11 | 2.309 | 1.479 | 33.249 | 31.770 | 30.291 |
https://amesweb.info/Screws/BSP-Thread-Chart.aspx
geminivalve.com says minor diameter (mm) is 30.292, as of 2026-08-12.
1 | 11 | 0.0909 | 2.309 | 1.309 | 33.249 | 1.1926 | 30.292 | 0.4091 | 10.391
Sources
- amesweb.infohttps://amesweb.info/Screws/BSP-Thread-Chart.aspx
- geminivalve.comhttps://www.geminivalve.com/bsp-thread-vs-npt-fitting/
- htsspares.comhttps://www.htsspares.com/blog/how-to/how-to-measure-your-bsp-fittings