# 3/4 Inch BSP — Plumbing fitting and pipe thread standards For 3/4 Inch BSP, thread standard is BSP; threads per inch (tpi) is 14; major (outside) diameter (mm) is 26.44, recorded from its source on 2026-08-12. - **Thread standard:** BSP _(our reading, not quoted from the source)_ - **Nominal size:** 3/4 Inch BSP _(verified: appears in the quote below)_ - **Threads per inch (TPI):** 14 _(verified: appears in the quote below)_ - **Major (outside) diameter (mm):** 26.44 _(verified: appears in the quote below)_ ## What the source says > 3/4 Inch BSP | 26.44 mm | 24.6 mm | 14 ## Source - https://www.lsengineers.co.uk/advice-centre/bsp-thread-sizes-explained Last verified: 2026-08-12. Review by: 2028-08-11. Part of [Plumbing fitting and pipe thread standards](https://referencesource.org/plumbing-fitting-thread-standards/).