UNC (Course Thread)
| TAP SIZE | DRILL SIZE |
| #0-80 | #56 (0.046”) |
| #1-64 | #53 (0.0595”) |
| #2-56 | #50 (0.070”) |
| #3-48 | #50 (0.070”) |
| #4-40 | #43 (0.089”) |
| #5-40 | #38 (0.1015”) |
| #6-32 | #36 (0.1065”) |
| #8-32 | #29 (0.136”) |
| #10-24 | #25 (0.1495”) |
| #12-24 | #16 (0.173”) |
| 1/4-20 | #7 (0.201”) |
| 5/16-18 | F (0.257”) |
| 3/8-16 | 5/16 (0.3125”) |
| 7/16-14 | U (0.368”) |
| 1/2-13 | 27/64 (0.4219”) |
| 9/16-12 | 31/64 (0.4844”) |
| 5/8-11 | 17/32 (0.5312”) |
| 3/4-10 | 21/32 (0.6562”) |
UNF (Fine Thread)
| #0-90 | #60 (0.040″) |
| #1-72 | #53 (0.0595″) |
| #2-64 | #50 (0.070″) |
| #3-48 | #47 (0.0785″) |
| #4-48 | #42 (0.0935″) |
| #5-44 | #38 (0.1015″) |
| #6-40 | #33 (0.113″) |
| #8-36 | #29 (0.136″) |
| #10-32 | #21 (0.159″) |
| #12-28 | #14 (0.182″) |
| 1/4-28 | #3 (0.213″) |
| 5/16-24 | I (0.272″) |
| 3/8-24 | Q (0.332″) |
| 7/16-20 | 25/64 (0.3906″) |
| 1/2-20 | 29/64 (0.4531″) |
| 9/16-18 | 33/64 (0.5156″) |
| 5/8-18 | 37/64 (0.5781″) |
| 3/4-16 | 11/16 (0.6875″) |