# 5/8 — Plumbing fitting and pipe thread standards

For 5/8, thread standard is NPT; threads per inch (tpi) is 14; major (outside) diameter (mm) is 22.9, recorded from its source on 2026-08-12.

- **Thread standard:** NPT _(our reading, not quoted from the source)_
- **Nominal size:** 5/8 _(verified: appears in the quote below)_
- **Threads per inch (TPI):** 14 _(verified: appears in the quote below)_
- **Major (outside) diameter (mm):** 22.9 _(verified: appears in the quote below)_

## What the source says

> -10 (5/8) | 14 | 22.9 | 0.90 | 21.1 | 0.83

## Source

- https://trimantec.com/blogs/t/thread-identification-guide

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/).