UNF — Unified fine

#5-44 UNF

Tap drill #37 for a #5-44 UNF thread — major Ø 3.175 mm, pitch 0.577 mm (44 TPI).

Tap-drill calculator Identify a thread

Tap drill

#37

2.64 mm · ≈71% thread

Profile

Thread form & key diameters

Dimensions

Designation	#5-44 UNF
Major (outside) diameter	3.175 mm · 0.125"
Pitch	0.577 mm · 44 TPI
Pitch diameter	2.8 mm · 0.1102"
Minor diameter (external)	2.467 mm · 0.0971"
Minor diameter (internal)	2.55 mm · 0.1004"
Recommended tap drill	#37 · 2.64 mm · ≈71% thread
Clearance hole	Close 9/64" · Normal 5/32" · Loose 3/16" — nominal + 1/64" / 1/32" / 1/16" to the nearest standard drill (common shop practice).
Socket key (across flats)	3/32"

Close 9/64" · Normal 5/32" · Loose 3/16" — nominal + 1/64" / 1/32" / 1/16" to the nearest standard drill (common shop practice).

What tap drill do I need for #5-44 UNF?

For a #5-44 UNF thread, drill the hole with a #37 tap drill (2.64 mm) before tapping. That produces roughly 71% thread engagement, the usual target for a strong, tappable hole. The mating bolt has a major diameter of 3.175 mm and a pitch of 0.577 mm (44 TPI).

To pass a #5-44 UNF bolt through a part rather than thread it, use a clearance hole: Close 9/64" · Normal 5/32" · Loose 3/16" — 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.

Same diameter

Other #5 threads

#5-40 UNCTap #38Ø 3.175 mm · pitch 0.635 mm

Nearby sizes

More unf — unified fine threads

#4-48 UNFTap #42Ø 2.845 mm · pitch 0.529 mm #6-40 UNFTap #33Ø 3.505 mm · pitch 0.635 mm #3-56 UNFTap #45Ø 2.515 mm · pitch 0.454 mm #2-64 UNFTap #50Ø 2.184 mm · pitch 0.397 mm #8-36 UNFTap #29Ø 4.166 mm · pitch 0.706 mm #1-72 UNFTap #53Ø 1.854 mm · pitch 0.353 mm #0-80 UNFTap 3/64"Ø 1.524 mm · pitch 0.318 mm #10-32 UNFTap #21Ø 4.826 mm · pitch 0.794 mm