| Size of Thread | Threads per inch | Std drill for approx 75% threads |
|---|---|---|
| 10 | 24 | No. 25 |
| 10 | 32 | No. 21 |
| 12 | 24 | No. 16 |
| 12 | 28 | No. 14 |
| 1/4 | 20 | No. 7 |
| 1/4 | 28 | No. 3 |
| 5/16 | 18 | F |
| 5/16 | 24 | I |
| 3/8 | 16 | 5/16 |
| 3/8 | 24 | Q |
| 7/16 | 14 | U |
| 7/16 | 20 | 25/64 |
| 1/2 | 13 | 27/64 |
| 1/2 | 20 | 29/64 |
| 9/16 | 12 | 31/64 |
| 9/16 | 18 | 33/64 |
| 5/8 | 11 | 17/32 |
| 5/8 | 18 | 37/64 |
| 3/4 | 10 | 21/32 |
| 3/4 | 16 | 11/16 |
| 7/8 | 9 | 49/64 |
| 7/8 | 14 | 13/16 |
| 1 | 8 | 7/8 |
| 1 | 14 | 15/16 |
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