#20 Drill Size

number drill

#20 0.161 in 4.09 mm

A #20 drill measures 0.161 in. It taps 2 threads in this chart.

What a #20 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 #20 drill taps, with the percent of thread each one gets and the published chart drill for comparison.
Thread	% thread	Chart drill	Chart %
#10-32	71.4%	#21	76.4%
#10-24	53.6%	#25	74.8%

Drills either side

#21 0.159 in · 4.04 mm Next size down
4.1 mm 0.1614 in · 4.1 mm Next size up

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

#20 drill: common questions

What size is a #20 drill?

0.161 inches, which is 4.09 mm. It is a number drill.

What can I tap with a #20 drill?

2 threads: #10-32 at 71.4%, #10-24 at 53.6%.

What drill is next to a #20?

Down: #21 at 0.159 in. Up: 4.1 mm at 0.1614 in.