2.5 mm Drill Size

metric drill

2.5 mm 0.0984 in 2.50 mm

A 2.5 mm drill is the standard tap drill for M3 x 0.5.

What a 2.5 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 2.5 mm drill taps, with the percent of thread each one gets and the published chart drill for comparison.
Thread	% thread	Chart drill	Chart %
#5-40	81.9%	#38	72.4%
M3 x 0.5 chart drill	77.0%	2.5 mm	77.0%
#4-48	50.3%	#42	68.4%

Drills either side

#40 0.098 in · 2.49 mm Next size down
#39 0.0995 in · 2.53 mm Next size up

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

2.5 mm drill: common questions

What size is a 2.5 mm drill?

0.0984 inches, which is 2.50 mm. It is a metric drill.

What can I tap with a 2.5 mm drill?

3 threads: #5-40 at 81.9%, M3 x 0.5 at 77.0%, #4-48 at 50.3%.

Is a 2.5 mm drill the standard tap drill for anything?

Yes, for M3 x 0.5 (77.0% thread). That is the size published tap and drill charts give.

What drill is next to a 2.5 mm?

Down: #40 at 0.098 in. Up: #39 at 0.0995 in.