1-1/4-11.5 NPT vs R1/2: 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 20.955 mm.
| Spec | 1-1/4-11.5 NPT | R1/2 |
|---|---|---|
| Designation | 1-1/4-11.5 NPT | R1/2 |
| Major diameter | 42.16 mm | 20.955 mm |
| Threads per inch / pitch | 11.5 | 14 |
| Thread form | tapered, 60 degree | tapered, 55 degree |
| Seals on | on the thread flanks with PTFE tape | on the thread flanks with PTFE tape or paste |
Questions and answers
Which has the higher major diameter, 1-1/4-11.5 NPT or R1/2?
On major diameter, 1-1/4-11.5 NPT leads: 42.16 mm versus 20.955 mm.
How do 1-1/4-11.5 NPT and R1/2 compare?
On major diameter, 1-1/4-11.5 NPT leads: 42.16 mm versus 20.955 mm.