G1-1/4 vs 1-1/4-11.5 NPT: specs compared
Updated 05 September 2026.
42.16 mm
1-1/4-11.5 NPT wins on major diameter
On major diameter, 1-1/4-11.5 NPT leads: 42.16 mm versus 41.91 mm.
| Spec | G1-1/4 | 1-1/4-11.5 NPT |
|---|---|---|
| Designation | G1-1/4 | 1-1/4-11.5 NPT |
| Major diameter | 41.91 mm | 42.16 mm |
| Threads per inch / pitch | 11 | 11.5 |
| Thread form | parallel, 55 degree | tapered, 60 degree |
| Seals on | flat washer or bonded seal on the face | on the thread flanks with PTFE tape |
Questions and answers
Which has the higher major diameter, G1-1/4 or 1-1/4-11.5 NPT?
On major diameter, 1-1/4-11.5 NPT leads: 42.16 mm versus 41.91 mm.
How do G1-1/4 and 1-1/4-11.5 NPT compare?
On major diameter, 1-1/4-11.5 NPT leads: 42.16 mm versus 41.91 mm.