31.5 mm Drill Size

metric drill

31.5 mm 1.2402 in 31.50 mm

A 31.5 mm drill measures 1.2402 in. It taps 2 threads in this chart.

What a 31.5 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 31.5 mm drill taps, with the percent of thread each one gets and the published chart drill for comparison.
Thread	% thread	Chart drill	Chart %
1-3/8-6	62.3%	1-7/32″	72.1%
M33 x 2	57.7%	31 mm	77.0%

Other jobs for a 31.5 mm

Hard-material tap drill: The size to use in stainless or tool steel for M33 x 2, where it leaves a shallower thread than the standard drill and cuts tapping torque.
Form-tap hole: The published roll-tap hole for M33 x 3.5. A form tap displaces metal instead of cutting it, so it needs this larger hole.

Drills either side

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

31.5 mm drill: common questions

What size is a 31.5 mm drill?

1.2402 inches, which is 31.50 mm. It is a metric drill.

What can I tap with a 31.5 mm drill?

2 threads: 1-3/8-6 at 62.3%, M33 x 2 at 57.7%.

What drill is next to a 31.5 mm?

Down: 1-15/64 in at 1.2344 in. Up: 1-1/4 in at 1.250 in.