#5-40 UNC tap drill size

#38 drill — 0.1015 in / 2.58 mm (72% thread)

Major Ø 0.1250 in · 40 threads per inch · coarse series. The chart pick targets 75% thread; nearby standard drills:

Drill	Decimal (in)	mm	Thread %
#37	0.1040	2.64	65%
#38	0.1015	2.58	72%
#39	0.0995	2.53	79%
#40	0.0980	2.49	83%

Cut taps only — roll-form taps need a larger hole. 65–75% suits general work; drop toward 55% in tough material. Verify before you cut.

Same size, fine series: #5-44 UNF