1/4-20 UNC tap drill size

#7 drill — 0.2010 in / 5.11 mm (75% thread)

Major Ø 0.2500 in · 20 threads per inch · coarse series. The chart pick targets 75% thread; nearby standard drills:

Drill	Decimal (in)	mm	Thread %
#6	0.2040	5.18	71%
13/64	0.2031	5.16	72%
#7	0.2010	5.11	75%
#8	0.1990	5.05	79%

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: 1/4-28 UNF