3.5 mm Drill Size

metric drill

3.5 mm 0.1378 in 3.50 mm

A 3.5 mm drill measures 0.1378 in. It taps 3 threads in this chart.

What a 3.5 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 3.5 mm drill taps, with the percent of thread each one gets and the published chart drill for comparison.
Thread	% thread	Chart drill	Chart %
#8-36	72.6%	#29	77.6%
#8-32	64.5%	#29	69.0%
M4 x 0.7	55.0%	3.3 mm	77.0%

Other jobs for a 3.5 mm

Hard-material tap drill: The size to use in stainless or tool steel for M4 x 0.7, where it leaves a shallower thread than the standard drill and cuts tapping torque.

Drills either side

#29 0.136 in · 3.45 mm Next size down
#28 0.1405 in · 3.57 mm Next size up

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

3.5 mm drill: common questions

What size is a 3.5 mm drill?

0.1378 inches, which is 3.50 mm. It is a metric drill.

What can I tap with a 3.5 mm drill?

3 threads: #8-36 at 72.6%, #8-32 at 64.5%, M4 x 0.7 at 55.0%.

What drill is next to a 3.5 mm?

Down: #29 at 0.136 in. Up: #28 at 0.1405 in.