From my experience, finding the right drill size for screws or bolts can be really tricky without a handy tap drill chart. There’s a lot to consider, like threads per inch and drill diameter. But don’t worry, I’ve put together all the key info in a simple table for you.
THREAD SIZE | FRACTIONAL (in.) |
DRILL DIAMETER
| TAP DRILL SIZE |
|---|---|---|---|
Coarse Thread | |||
1/64 | – | .0595 | No. 53 |
2-56 | – | .0700 | No. 50 |
3-48 | – | .0785 | No. 47 |
4-40 | 3/32” | .0890 | No. 43 |
5-40 | – | .1015 | No. 38 |
6-32 | 7/64” | .1065 | No. 36 |
8-32 | – | .1360 | No. 29 |
10-24 | 5/32” | .1495 | No. 25 |
12-24 | 11/64” | .1770 | No. 16 |
1/4-20 | 13/64” | .2010 | No. 7 |
5/16-18 | 17/64” | .2570 | ‘F’ |
3/8-6 | 1 7/32” | 1.2188 | – |
3/8-16 | 5/16” | .3125 | 5/16 |
7/16-14 | 23/64” | .3680 | ‘U’ |
1/2-13 | 27/64” | .4219 | 27/64 |
9/16-12 | 31/64” | .4844 | 31/64 |
5/8-11 | 17/32” | .5312 | 17/32 |
3/4-10 | 21/32” | .6562 | 21/32 |
7/8-9 | – | .7656 | 49/64 |
1″-8 | – | .8750 | 7/8 |
1-1/2 | – | 1.882 | 1-25/32” |
1 1/2 6 | 1 11/32” | 1.3438 | – |
1 1/4-7 | 1 7/64” | 1.1094 | – |
Fine Thread | |||
0-80 | 3/64” | .0469 | 3/64 |
1-72 | – | .0595 | No. 53 |
2-64 | – | .0700 | No. 50 |
3-56 | – | .0820 | No. 45 |
4-48 | – | .0935 | No. 42 |
5-44 | – | .1040 | No. 37 |
6-40 | – | .1130 | No. 33 |
8-36 | – | .1360 | No. 29 |
10-32 | 5/32” | .1590 | No. 21 |
12-28 | – | .1820 | No. 14 |
1/4-28 | 7/32” | .2130 | No. 3 |
5/16-24 | – | .2720 | ‘I’ |
3/8-24 | 21/64” | .3320 | ‘Q’ |
7/16-20 | 25/64” | .3906 | 25/64 |
1/2-20 | 29/64” | .4531 | 29/64 |
9/16-18 | 33/64” | .5156 | 33/64 |
5/8-18 | 37/64” | .5781 | 37/64 |
3/4-16 | 11/16” | .6875 | 11/16 |
7/8-14 | – | .8125 | 13/16 |
1″-14 | – | .9375 | 59/64 |
NS (Special Thread) | |||
7/8 -18 | 53/64” | .8281 | 53/64” |
11/16-11 | 19/32” | .5938 | – |
1-14 | 15/16” | .9375 | – |
NEF (Ultra Fine Thread) | |||
5/16-32 | 9/32” | .2812 | 8/32” |
*Drill sizes are for 75% of the total depth of the thread.
Robert Johnson is a passionate furniture maker & carpenter, sought after for his knowledge on the craft.
You’ve probably seen his down-to-earth wisdom in USA Today, Bobvila, Family Handyman, and The Spruce, where he has shared commentary and guidance on various woodworking topics.
Robert is the brain behind Sawinery, where he aims to share tips, tricks, and a passion for all things carpentry.
