9/16-12 UNC tap drill size

31/64 drill — 0.4844 in / 12.30 mm (72% thread)

Major Ø 0.5625 in · 12 threads per inch · coarse series. The chart pick targets 75% thread; nearby standard drills:

Drill	Decimal (in)	mm	Thread %
1/2	0.5000	12.70	58%
31/64	0.4844	12.30	72%
15/32	0.4688	11.91	87%
29/64	0.4531	11.51	101%

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: 9/16-18 UNF