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.
To give you a quick and easy reference that considers all the details, we listed them in a neat and tidy table.
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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