2-11.5 NPT vs R2-1/2: specs compared

Updated 05 September 2026.

75.184 mm
R2-1/2 wins on major diameter

On major diameter, R2-1/2 leads: 75.184 mm versus 60.32 mm.

Spec2-11.5 NPTR2-1/2
Designation2-11.5 NPTR2-1/2
Major diameter60.32 mm75.184 mm
Threads per inch / pitch11.511
Thread formtapered, 60 degreetapered, 55 degree
Seals onon the thread flanks with PTFE tapeon the thread flanks with PTFE tape or paste

Questions and answers

Which has the higher major diameter, 2-11.5 NPT or R2-1/2?

On major diameter, R2-1/2 leads: 75.184 mm versus 60.32 mm.

How do 2-11.5 NPT and R2-1/2 compare?

On major diameter, R2-1/2 leads: 75.184 mm versus 60.32 mm.

Compared here

2" NPT (National Pipe Taper) (2-11.5 NPT)2-1/2" BSP tapered (R2-1/2 / BSPT) (R2-1/2)