2.55 mm Drill Size

metric drill

2.55 mm 0.1004 in 2.55 mm

A 2.55 mm drill measures 0.1004 in. It taps 3 threads in this chart.

What a 2.55 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 2.55 mm drill taps, with the percent of thread each one gets and the published chart drill for comparison.
Thread	% thread	Chart drill	Chart %
#5-44	83.3%	#37	71.1%
#5-40	75.7%	#38	72.4%
M3 x 0.5	69.3%	2.5 mm	77.0%

Drills either side

#39 0.0995 in · 2.53 mm Next size down
#38 0.1015 in · 2.58 mm Next size up

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

2.55 mm drill: common questions

What size is a 2.55 mm drill?

0.1004 inches, which is 2.55 mm. It is a metric drill.

What can I tap with a 2.55 mm drill?

3 threads: #5-44 at 83.3%, #5-40 at 75.7%, M3 x 0.5 at 69.3%.

What drill is next to a 2.55 mm?

Down: #39 at 0.0995 in. Up: #38 at 0.1015 in.