#42 Drill Size

number drill

#42 0.0935 in 2.38 mm

A #42 drill is the standard tap drill for #4-48.

What a #42 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 #42 drill taps, with the percent of thread each one gets and the published chart drill for comparison.
Thread	% thread	Chart drill	Chart %
#4-48 chart drill	68.4%	#42	68.4%
#4-40	57.0%	#43	70.8%

Other jobs for a #42

Hard-material tap drill: The size to use in stainless or tool steel for #4-40, where it leaves a shallower thread than the standard drill and cuts tapping torque.

Drills either side

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

#42 drill: common questions

What size is a #42 drill?

0.0935 inches, which is 2.38 mm. It is a number drill.

What can I tap with a #42 drill?

2 threads: #4-48 at 68.4%, #4-40 at 57.0%.

Is a #42 drill the standard tap drill for anything?

Yes, for #4-48 (68.4% thread). That is the size published tap and drill charts give.

What drill is next to a #42?

Down: 2.35 mm at 0.0925 in. Up: 3/32 in at 0.0938 in.