Without a reliable tap drill chart, determining the appropriate drill size for your screws or bolts is next to impossible.
That’s because there are so many factors to take into account including the threads per inch, drill diameter, and the tap drill sizes.
We have compiled all the essential details in a neat and tidy table for your quick and easy reference.
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.
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