NPT — American tapered pipe

1/2-14 NPT

1/2-14 NPT pipe thread: 14 TPI, major Ø 21.34 mm.

Tap-drill calculator Identify a thread

Tap drill

17.86 mm

21.34 mm major Ø

Profile

Thread form & key diameters

Dimensions

Designation	1/2-14 NPT
Major (outside) diameter	21.34 mm · 0.8402"
Pitch	1.814 mm · 14 TPI
Pitch diameter	20.162 mm · 0.7938"
Minor diameter (external)	19.114 mm · 0.7525"
Minor diameter (internal)	19.376 mm · 0.7628"
Recommended tap drill	17.86 mm

What tap drill do I need for 1/2-14 NPT?

1/2-14 NPT is a NPT pipe thread running at 14 threads per inch on a 21.34 mm major diameter. NPT is a 60° tapered thread that seals on the flanks; use a tapered reamer after drilling for a full-form thread.

All values are generated from the standard thread formulas (ISO 68-1 / ASME B1.1) and published standard tables — not hand-entered. See the full reference.

Nearby sizes

More npt — american tapered pipe threads

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