threadcalc.
ReferenceHelp

NPSM straight pipe

NPSM provides straight mechanical pipe-thread limits. Its nominal pipe size remains distinct from the actual thread diameter.

Open calculator

Example designation

1/8-27 NPSM

1/8
Nominal pipe size.
27
Threads per inch.
NPSM
Straight mechanical pipe thread family.
Calculate this example

Straight-thread inspection

Use the external major- and pitch-diameter limits for the male thread, and the internal pitch- and minor-diameter limits for the female thread. The external inspection result uses three wires.

Retain the mechanical-thread designation

NPSM and NPT can share a nominal size and TPI while having different thread geometry. Keep the NPSM suffix when specifying the straight-thread part or its mating component.