J Drill Size

letter drill

J 0.277 in 7.04 mm

A J drill measures 0.277 in. It taps 3 threads in this chart.

What a J 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 J drill taps, with the percent of thread each one gets and the published chart drill for comparison.
Thread	% thread	Chart drill	Chart %
M8 x 1	74.2%	7 mm	77.0%
5/16-24	65.6%	I	74.8%
M8 x 1.25	59.4%	6.8 mm	73.9%

Drills either side

7 mm 0.2756 in · 7 mm Next size down
7.1 mm 0.2795 in · 7.1 mm Next size up

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

J drill: common questions

What size is a J drill?

0.277 inches, which is 7.04 mm. It is a letter drill.

What can I tap with a J drill?

3 threads: M8 x 1 at 74.2%, 5/16-24 at 65.6%, M8 x 1.25 at 59.4%.

What drill is next to a J?

Down: 7 mm at 0.2756 in. Up: 7.1 mm at 0.2795 in.