G1/4 vs R1/8: specs compared
Updated 05 September 2026.
13.157 mm
G1/4 wins on major diameter
On major diameter, G1/4 leads: 13.157 mm versus 9.728 mm.
| Spec | G1/4 | R1/8 |
|---|---|---|
| Designation | G1/4 | R1/8 |
| Major diameter | 13.157 mm | 9.728 mm |
| Threads per inch / pitch | 19 | 28 |
| Thread form | parallel, 55 degree | tapered, 55 degree |
| Seals on | flat washer or bonded seal on the face | on the thread flanks with PTFE tape or paste |
Questions and answers
Which has the higher major diameter, G1/4 or R1/8?
On major diameter, G1/4 leads: 13.157 mm versus 9.728 mm.
How do G1/4 and R1/8 compare?
On major diameter, G1/4 leads: 13.157 mm versus 9.728 mm.