L Drill Size

letter drill

L 0.290 in 7.37 mm

A L drill measures 0.290 in. It taps 2 threads in this chart.

What a L 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 L drill taps, with the percent of thread each one gets and the published chart drill for comparison.
Thread	% thread	Chart drill	Chart %
M8 x 0.75	65.1%	7.3 mm	71.9%
5/16-32	55.4%	9/32″	77.1%

Other jobs for a L

Hard-material tap drill: The size to use in stainless or tool steel for 5/16-32, where it leaves a shallower thread than the standard drill and cuts tapping torque.
Form-tap hole: The published roll-tap hole for 5/16-18. 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 →

L drill: common questions

What size is a L drill?

0.290 inches, which is 7.37 mm. It is a letter drill.

What can I tap with a L drill?

2 threads: M8 x 0.75 at 65.1%, 5/16-32 at 55.4%.

What drill is next to a L?

Down: 7.3 mm at 0.2874 in. Up: 7.4 mm at 0.2913 in.