Unified Cut Tap Drills
51 rows
Cut-tap drill sizes for Unified inch threads, with the percentage of thread each drill gives. For another thread percentage, or the drills either side, use the Tap Drill Calculator.
| Tap | TPI | Cut tap drill | Thread % |
|---|---|---|---|
| #0 UNF | 80 | 3/64 | 81% |
| #1 UNC | 64 | #53 | 67% |
| #1 UNF | 72 | #53 | 75% |
| #2 UNC | 56 | #51 | 82% |
| #2 UNF | 64 | #50 | 79% |
| #3 UNC | 48 | 5/64 | 77% |
| #3 UNF | 56 | #46 | 78% |
| #4 UNC | 40 | #43 | 71% |
| #4 UNF | 48 | #42 | 68% |
| #5 UNC | 40 | #39 | 79% |
| #5 UNF | 44 | #37 | 71% |
| #6 UNC | 32 | #36 | 78% |
| #6 UNF | 40 | #33 | 77% |
| #8 UNC | 32 | #29 | 69% |
| #8 UNF | 36 | #29 | 78% |
| #10 UNC | 24 | #25 | 75% |
| #10 UNF | 32 | #21 | 76% |
| #12 UNC | 24 | #17 | 79% |
| #12 UNF | 28 | #15 | 78% |
| 1/4 UNC | 20 | #7 | 75% |
| 1/4 UNF | 28 | #3 | 80% |
| 5/16 UNC | 18 | F | 77% |
| 5/16 UNF | 24 | I | 75% |
| 3/8 UNC | 16 | 5/16 | 77% |
| 3/8 UNF | 24 | Q | 79% |
| 7/16 UNC | 14 | U | 75% |
| 7/16 UNF | 20 | W | 79% |
| 1/2 UNC | 13 | 27/64 | 78% |
| 1/2 UNF | 20 | 29/64 | 72% |
| 9/16 UNC | 12 | 31/64 | 72% |
| 9/16 UNF | 18 | 33/64 | 65% |
| 5/8 UNC | 11 | 17/32 | 79% |
| 5/8 UNF | 18 | 37/64 | 65% |
| 3/4 UNC | 10 | 21/32 | 72% |
| 3/4 UNF | 16 | 11/16 | 77% |
| 7/8 UNC | 9 | 49/64 | 76% |
| 7/8 UNF | 14 | 13/16 | 67% |
| 1 UNC | 8 | 7/8 | 77% |
| 1 UNF | 12 | 59/64 | 72% |
| 1-1/8 UNC | 7 | 63/64 | 76% |
| 1-1/8 UNF | 12 | 1-3/64 | 72% |
| 1-1/4 UNC | 7 | 1-7/64 | 76% |
| 1-1/4 UNF | 12 | 1-11/64 | 72% |
| 1-3/8 UNC | 6 | 1-13/64 | 79% |
| 1-3/8 UNF | 12 | 1-19/64 | 72% |
| 1-1/2 UNC | 6 | 1-11/32 | 72% |
| 1-1/2 UNF | 12 | 1-27/64 | 72% |
| 1-3/4 UNC | 5 | 1-35/64 | 78% |
| 1-3/4 UN | 12 | 1-43/64 | 72% |
| 2 UNC | 4-1/2 | 1-25/32 | 76% |
| 2 UN | 12 | 1-59/64 | 72% |
Based on NBS Handbook H28 (1969), Part I, Appendix A3