Tap Drill Size Chart

#3 Drill Size

number drill

#3 0.213 in 5.41 mm

A #3 drill is the standard tap drill for 1/4-28.

What a #3 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 drill taps, with the percent of thread each one gets and the published chart drill for comparison.
Thread % thread Chart drill Chart %
1/4-28 chart drill 79.8% #3 79.8%
1/4-20 57.0% #7 75.4%

Other jobs for a #3

Hard-material tap drill
The size to use in stainless or tool steel for 1/4-20, where it leaves a shallower thread than the standard drill and cuts tapping torque.
Clearance hole
The through hole a bolt passes in, not a tapped hole: loose fit for #8-32, loose fit for #8-36. See the clearance hole chart.

Drills either side

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

#3 drill: common questions

What size is a #3 drill?
0.213 inches, which is 5.41 mm. It is a number drill.
What can I tap with a #3 drill?
2 threads: 1/4-28 at 79.8%, 1/4-20 at 57.0%.
Is a #3 drill the standard tap drill for anything?
Yes, for 1/4-28 (79.8% thread). That is the size published tap and drill charts give.
Is a #3 drill used for clearance holes?
Yes: loose fit for #8-32, loose fit for #8-36. A clearance hole is not tapped; the bolt passes through it.
What drill is next to a #3?
Down: 5.4 mm at 0.2126 in. Up: 5.5 mm at 0.2165 in.