2-11.5 NPT vs 2-1/2-8 NPT: specs compared

Updated 05 September 2026.

73.02 mm
2-1/2-8 NPT wins on major diameter

On major diameter, 2-1/2-8 NPT leads: 73.02 mm versus 60.32 mm.

Spec2-11.5 NPT2-1/2-8 NPT
Designation2-11.5 NPT2-1/2-8 NPT
Major diameter60.32 mm73.02 mm
Threads per inch / pitch11.58
Thread formtapered, 60 degreetapered, 60 degree
Seals onon the thread flanks with PTFE tapeon the thread flanks with PTFE tape

Questions and answers

Which has the higher major diameter, 2-11.5 NPT or 2-1/2-8 NPT?

On major diameter, 2-1/2-8 NPT leads: 73.02 mm versus 60.32 mm.

How do 2-11.5 NPT and 2-1/2-8 NPT compare?

On major diameter, 2-1/2-8 NPT leads: 73.02 mm versus 60.32 mm.

Compared here

2" NPT (National Pipe Taper) (2-11.5 NPT)2-1/2" NPT (National Pipe Taper) (2-1/2-8 NPT)