6-8 NPT vs M18 x 1 male: specs compared
Updated 05 September 2026.
168.27 mm
6-8 NPT wins on major diameter
On major diameter, 6-8 NPT leads: 168.27 mm versus 18 mm.
| Spec | 6-8 NPT | M18 x 1 male |
|---|---|---|
| Designation | 6-8 NPT | M18 x 1 male |
| Major diameter | 168.27 mm | 18.0 mm |
| Threads per inch / pitch | 8 | 1 mm pitch |
| Thread form | tapered, 60 degree | fine parallel |
| Seals on | on the thread flanks with PTFE tape | washer inside the aerator housing |
Questions and answers
Which has the higher major diameter, 6-8 NPT or M18 x 1 male?
On major diameter, 6-8 NPT leads: 168.27 mm versus 18 mm.
How do 6-8 NPT and M18 x 1 male compare?
On major diameter, 6-8 NPT leads: 168.27 mm versus 18 mm.