UNF — Unified fine

#0-80 UNF

Tap drill 3/64" for a #0-80 UNF thread — major Ø 1.524 mm, pitch 0.318 mm (80 TPI).

Tap-drill calculator Identify a thread

Tap drill

3/64"

1.19 mm · ≈81% thread

Profile

Thread form & key diameters

Dimensions

Designation	#0-80 UNF
Major (outside) diameter	1.524 mm · 0.06"
Pitch	0.318 mm · 80 TPI
Pitch diameter	1.318 mm · 0.0519"
Minor diameter (external)	1.134 mm · 0.0447"
Minor diameter (internal)	1.18 mm · 0.0465"
Recommended tap drill	3/64" · 1.19 mm · ≈81% thread
Clearance hole	Close #48 · Normal #42 · Loose 1/8" — nominal + 1/64" / 1/32" / 1/16" to the nearest standard drill (common shop practice).
Socket key (across flats)	0.050"

Close #48 · Normal #42 · Loose 1/8" — nominal + 1/64" / 1/32" / 1/16" to the nearest standard drill (common shop practice).

What tap drill do I need for #0-80 UNF?

For a #0-80 UNF thread, drill the hole with a 3/64" tap drill (1.19 mm) before tapping. That produces roughly 81% thread engagement, the usual target for a strong, tappable hole. The mating bolt has a major diameter of 1.524 mm and a pitch of 0.318 mm (80 TPI).

To pass a #0-80 UNF bolt through a part rather than thread it, use a clearance hole: Close #48 · Normal #42 · Loose 1/8" — nominal + 1/64" / 1/32" / 1/16" to the nearest standard drill (common shop practice)..

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 unf — unified fine threads

#1-72 UNFTap #53Ø 1.854 mm · pitch 0.353 mm #2-64 UNFTap #50Ø 2.184 mm · pitch 0.397 mm #3-56 UNFTap #45Ø 2.515 mm · pitch 0.454 mm #4-48 UNFTap #42Ø 2.845 mm · pitch 0.529 mm #5-44 UNFTap #37Ø 3.175 mm · pitch 0.577 mm #6-40 UNFTap #33Ø 3.505 mm · pitch 0.635 mm #8-36 UNFTap #29Ø 4.166 mm · pitch 0.706 mm #10-32 UNFTap #21Ø 4.826 mm · pitch 0.794 mm