31/64 in Drill Size

fractional drill

31/64″ 0.4844 in 12.30 mm

A 31/64 in drill is the standard tap drill for 9/16-12.

What a 31/64 in 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 31/64 in drill taps, with the percent of thread each one gets and the published chart drill for comparison.
Thread	% thread	Chart drill	Chart %
9/16-12 chart drill	72.1%	31/64″	72.1%
M14 x 2	65.3%	12 mm	77.0%

Other jobs for a 31/64 in

Form-tap hole: The published roll-tap hole for 1/2-20, 1/2-28. A form tap displaces metal instead of cutting it, so it needs this larger hole.
Clearance hole: The through hole a bolt passes in, not a tapped hole: loose fit for 7/16-14, loose fit for 7/16-20, loose fit for 7/16-28. See the clearance hole chart.

Drills either side

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31/64 in drill: common questions

What size is a 31/64 in drill?

0.4844 inches, which is 12.30 mm. It is a fractional drill.

What can I tap with a 31/64 in drill?

2 threads: 9/16-12 at 72.1%, M14 x 2 at 65.3%.

Is a 31/64 in drill the standard tap drill for anything?

Yes, for 9/16-12 (72.1% thread). That is the size published tap and drill charts give.

Is a 31/64 in drill used for clearance holes?

Yes: loose fit for 7/16-14, loose fit for 7/16-20, loose fit for 7/16-28. A clearance hole is not tapped; the bolt passes through it.

What drill is next to a 31/64 in?

Down: 12.3 mm at 0.4843 in. Up: 12.4 mm at 0.4882 in.