Tap Drill Size Chart

U Drill Size

letter drill

U 0.368 in 9.35 mm

A U drill is the standard tap drill for 7/16-14.

What a U drill taps

Every thread this drill cuts between 50% and 85% of thread, deepest first. Outside that band it is the wrong drill for the job, so nothing below that line is listed.

Threads a U drill taps, with the percent of thread each one gets and the published chart drill for comparison.
Thread % thread Chart drill Chart %
7/16-14 chart drill 74.9% U 74.9%
M10 x 0.75 67.0% 9.3 mm 71.9%
M10 x 1 50.3% 9 mm 77.0%

Drills either side

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U drill: common questions

What size is a U drill?
0.368 inches, which is 9.35 mm. It is a letter drill.
What can I tap with a U drill?
3 threads: 7/16-14 at 74.9%, M10 x 0.75 at 67.0%, M10 x 1 at 50.3%.
Is a U drill the standard tap drill for anything?
Yes, for 7/16-14 (74.9% thread). That is the size published tap and drill charts give.
What drill is next to a U?
Down: 9.3 mm at 0.3661 in. Up: 9.4 mm at 0.3701 in.