1-1/8-12 UNF tap drill size

1-3/64 drill — 1.0469 in / 26.59 mm (72% thread)

Major Ø 1.1250 in · 12 threads per inch · fine series. The chart pick targets 75% thread; nearby standard drills:

Drill	Decimal (in)	mm	Thread %
1-1/16	1.0625	26.99	58%
1-3/64	1.0469	26.59	72%
1-1/32	1.0313	26.19	87%
1-1/64	1.0156	25.80	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, coarse series: 1-1/8-7 UNC