1/2-14 NPT vs 1/4-18 NPT: specs compared

Updated 05 September 2026.

21.34 mm
1/2-14 NPT wins on major diameter

On major diameter, 1/2-14 NPT leads: 21.34 mm versus 13.72 mm.

Spec1/2-14 NPT1/4-18 NPT
Designation1/2-14 NPT1/4-18 NPT
Major diameter21.34 mm13.72 mm
Threads per inch / pitch1418
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, 1/2-14 NPT or 1/4-18 NPT?

On major diameter, 1/2-14 NPT leads: 21.34 mm versus 13.72 mm.

How do 1/2-14 NPT and 1/4-18 NPT compare?

On major diameter, 1/2-14 NPT leads: 21.34 mm versus 13.72 mm.

Compared here

1/2" NPT (National Pipe Taper) (1/2-14 NPT)1/4" NPT (National Pipe Taper) (1/4-18 NPT)