H Drill Size

letter drill

H 0.266 in 6.76 mm

A H drill measures 0.266 in. It taps 2 threads in this chart.

What a H 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 H drill taps, with the percent of thread each one gets and the published chart drill for comparison.
Thread	% thread	Chart drill	Chart %
M8 x 1.25	76.6%	6.8 mm	73.9%
5/16-18	64.4%	F	76.9%

Drills either side

17/64″ 0.2656 in · 6.75 mm Next size down
6.8 mm 0.2677 in · 6.8 mm Next size up

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

H drill: common questions

What size is a H drill?

0.266 inches, which is 6.76 mm. It is a letter drill.

What can I tap with a H drill?

2 threads: M8 x 1.25 at 76.6%, 5/16-18 at 64.4%.

What drill is next to a H?

Down: 17/64 in at 0.2656 in. Up: 6.8 mm at 0.2677 in.