1/2-20 UNF tap drill size

29/64 drill — 0.4531 in / 11.51 mm (72% thread)

Major Ø 0.5000 in · 20 threads per inch · fine series. The chart pick targets 75% thread; nearby standard drills:

Drill	Decimal (in)	mm	Thread %
31/64	0.4844	12.30	24%
15/32	0.4688	11.91	48%
29/64	0.4531	11.51	72%
7/16	0.4375	11.11	96%

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, coarse series: 1/2-13 UNC