1/4-18 NPT vs R2: specs compared
Updated 05 September 2026.
59.614 mm
R2 wins on major diameter
On major diameter, R2 leads: 59.614 mm versus 13.72 mm.
| Spec | 1/4-18 NPT | R2 |
|---|---|---|
| Designation | 1/4-18 NPT | R2 |
| Major diameter | 13.72 mm | 59.614 mm |
| Threads per inch / pitch | 18 | 11 |
| 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, 1/4-18 NPT or R2?
On major diameter, R2 leads: 59.614 mm versus 13.72 mm.
How do 1/4-18 NPT and R2 compare?
On major diameter, R2 leads: 59.614 mm versus 13.72 mm.