Tap Drill Size Chart

9.9 mm Drill Size

metric drill

9.9 mm 0.3898 in 9.90 mm

A 9.9 mm drill measures 0.3898 in. It taps 2 threads in this chart.

What a 9.9 mm 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 9.9 mm drill taps, with the percent of thread each one gets and the published chart drill for comparison.
Thread % thread Chart drill Chart %
7/16-20 73.4% 25/64″ 72.2%
7/16-14 51.4% U 74.9%

Drills either side

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9.9 mm drill: common questions

What size is a 9.9 mm drill?
0.3898 inches, which is 9.90 mm. It is a metric drill.
What can I tap with a 9.9 mm drill?
2 threads: 7/16-20 at 73.4%, 7/16-14 at 51.4%.
What drill is next to a 9.9 mm?
Down: W at 0.386 in. Up: 25/64 in at 0.3906 in.