Part of the reason for this tap drill chart page is to make it handier for me to find. I’m going to, over time, put as many charts and tables on the internet as I can. At least the ones I use. Then when I need to look up something in one of the tables or charts that I know exist, I just go online and to my Chilipepper web site and presto! The data I need is readily at hand. I hope this chart proves useful to you as well.
Tap Drill Chart. Sizes for threads of American National Form |
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| Screw Thread | Commercial Tap Drill |
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| Outside Dia, Pitch |
Root Diameter | Size or Number | Decimal Equiv. |
| 1/16 – 64 | .0422 | 3/64 | .0469 |
| 72 | .0445 | 3/64 | .0469 |
| 5/64 – 60 | .0563 | 1/16 | .0625 |
| 72 | .0601 | 52 | .0635 |
| 3/32 – 48 | .0667 | 49 | .0730 |
| 50 | .0678 | 49 | .0730 |
| 7/64 – 48 | .0823 | 43 | .0890 |
| 1/8 – 32 | .0844 | 3/32 | .0937 |
| 40 | .0925 | 38 | .1015 |
| 9/64 – 40 | .1081 | 32 | .1160 |
| 5/32 – 32 | .1157 | 1/8 | .1250 |
| 36 | .1202 | 30 | .1285 |
| 11/64 – 32 | .1313 | 9/64 | .1406 |
| 3/16 – 24 | .1334 | 26 | .1470 |
| 32 | .1467 | 22 | .1570 |
| 13/64 – 24 | .1490 | 20 | .1610 |
| 7/32 – 24 | .1646 | 16 | .1770 |
| 32 | .1782 | 12 | .1890 |
| 15/64 – 24 | .1806 | 10 | .1935 |
| 1/4 – 20 | .1850 | 7 | .2010 |
| 24 | .1959 | 4 | .2090 |
| 27 | .2019 | 3 | .2130 |
| 28 | .2036 | 3 | .2130 |
| 32 | .2094 | 7/32 | .2187 |
| 5/16 – 18 | .2403 | F | .2570 |
| 20 | .2476 | 17/64 | .2656 |
| 24 | .2584 | I | .2720 |
| 27 | .2644 | J | .2770 |
| 32 | .2719 | 9/32 | .2812 |
| 3/8 – 16 | .2938 | 5/16 | .3125 |
| 20 | .3100 | 21/64 | .3281 |
| 24 | .3209 | Q | .3320 |
| 27 | .3269 | R | .3390 |
| 7/16 – 14 | .3447 | U | .3680 |
| 20 | .3726 | 25/64 | .3906 |
| 24 | .3834 | X | .3970 |
| 27 | .3894 | Y | .4040 |
| 1/2 – 12 | .3918 | 27/64 | .4219 |
| 13 | .4001 | 27/64 | .4219 |
| 20 | .4351 | 29/64 | .4531 |
| 24 | .4459 | 29/64 | .4531 |
| 27 | .4519 | 15/32 | .4687 |
| 9/16 – 12 | .4542 | 31/64 | .4844 |
| 18 | .4903 | 33/64 | .5156 |
| 27 | .5144 | 17/32 | .5312 |
| 5/8 – 11 | .5069 | 17/32 | .5312 |
| 12 | .5168 | 35/64 | .5469 |
| 18 | .5528 | 37/64 | .5781 |
| 27 | .5769 | 19/32 | .5937 |
| 11/16 – 11 | .5694 | 19/32 | .5937 |
| 16 | .6063 | 5/8 | .6250 |
| 3/4 – 10 | .6201 | 21/32 | .6562 |
| 12 | .6418 | 43/64 | .6719 |
| 16 | .6688 | 11/16 | .6875 |
| 27 | .7019 | 23/32 | .7187 |
| 13/16 – 10 | .6826 | 23/32 | .7187 |
| 7/8 9 | .7307 | 49/64 | .7656 |
| 12 | .7668 | 51/64 | .7969 |
| 14 | .7822 | 13/16 | .8125 |
| 18 | .8028 | 53/64 | .8281 |
| 27 | .8269 | 27/32 | .8437 |
| 15/16 – 9 | .7932 | 53/64 | .8281 |
| 1 – 8 | .8376 | 7/8 | .8750 |
| 12 | .8918 | 59/64 | .9219 |
| 14 | .9072 | 15/16 | .9375 |
| 27 | .9519 | 3132 | .9687 |
| 1 1/8 – 7 | .9394 | 63/64 | .9844 |
| 12 | 1.0168 | 1-3/64 | 1.0469 |
| 1 1/4 – 7 | 1.0644 | 1-7/64 | 1.1094 |
| 12 | 1.1418 | 1-11/64 | 1.1719 |
| 1 3/8 – 6 | 1.1585 | 1-7/32 | 1.2187 |
| 12 | 1.2668 | 1-19/64 | 1.2969 |
| 1 1/2 – 6 | 1.2835 | 1-11/32 | 1.3437 |
| 12 | 1.3918 | 1-27/64 | 1.4219 |
| 1 5/8 – 5 1/2 | 1.3888 | 1-29/64 | 1.4531 |
| 1 3/4 – 5 | 1.4902 | 1-9/16 | 1.5625 |
| 1 7/8 – 5 | 1.6152 | 1-11/16 | 1.6875 |
| 2 – 4 1/2 | 1.7113 | 1-25/32 | 1.7812 |
| 2 1/8 – 4 1/2 | 1.8363 | 1-29/32 | 1.9062 |
| 2 1/4 – 4 1/2 | 1.9613 | 2-1/32 | 2.0312 |
| 2 3/8 – 4 | 2.0502 | 2-1/8 | 2.1250 |
| 2 1/2 – 4 | 2.1752 | 2-1/4 | 2.2500 |