31 mm Drill Size

metric drill

31 mm 1.2205 in 31.00 mm

A 31 mm drill is the standard tap drill for M33 x 2.

What a 31 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 31 mm drill taps, with the percent of thread each one gets and the published chart drill for comparison.
Thread	% thread	Chart drill	Chart %
M33 x 2 chart drill	77.0%	31 mm	77.0%
1-3/8-6	71.4%	1-7/32″	72.1%

Drills either side

1-7/32″ 1.2188 in · 30.96 mm Next size down
1-15/64″ 1.2344 in · 31.35 mm Next size up

All drill sizes → · Open this drill in the calculator →

31 mm drill: common questions

What size is a 31 mm drill?

1.2205 inches, which is 31.00 mm. It is a metric drill.

What can I tap with a 31 mm drill?

2 threads: M33 x 2 at 77.0%, 1-3/8-6 at 71.4%.

Is a 31 mm drill the standard tap drill for anything?

Yes, for M33 x 2 (77.0% thread). That is the size published tap and drill charts give.

What drill is next to a 31 mm?

Down: 1-7/32 in at 1.2188 in. Up: 1-15/64 in at 1.2344 in.