#30 Drill Size

number drill

#30 0.1285 in 3.26 mm

A #30 drill measures 0.1285 in. It taps 1 thread in this chart.

What a #30 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 #30 drill taps, with the percent of thread each one gets and the published chart drill for comparison.
Thread	% thread	Chart drill	Chart %
M4 x 0.7	80.9%	3.3 mm	77.0%

Other jobs for a #30

Form-tap hole: The published roll-tap hole for #6-40. A form tap displaces metal instead of cutting it, so it needs this larger hole.
Clearance hole: The through hole a bolt passes in, not a tapped hole: loose fit for #3-48, normal fit for #4-40, loose fit for #3-56, normal fit for #4-48. See the clearance hole chart.

Drills either side

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#30 drill: common questions

What size is a #30 drill?

0.1285 inches, which is 3.26 mm. It is a number drill.

What can I tap with a #30 drill?

1 thread: M4 x 0.7 at 80.9%.

Is a #30 drill used for clearance holes?

Yes: loose fit for #3-48, normal fit for #4-40, loose fit for #3-56, normal fit for #4-48. A clearance hole is not tapped; the bolt passes through it.

What drill is next to a #30?

Down: #31 at 0.120 in. Up: 3.3 mm at 0.1299 in.