Tap drill chart
Common UNC, UNF and metric threads with the drill for about 75% thread.
| Thread | Ideal for 75% | Drill | Thread % |
|---|---|---|---|
| #4-40 | 0.0876 in | #43 (0.0890 in) | 71% |
| #6-32 | 0.1076 in | #36 (0.1065 in) | 78% |
| #8-32 | 0.1336 in | #29 (0.1360 in) | 69% |
| #10-24 | 0.1494 in | #25 (0.1495 in) | 75% |
| #10-32 | 0.1596 in | #21 (0.1590 in) | 76% |
| 1/4"-20 | 0.2013 in | #7 (0.2010 in) | 75% |
| 1/4"-28 | 0.2152 in | #3 (0.2130 in) | 80% |
| 5/16"-18 | 0.2584 in | F (0.2570 in) | 77% |
| 5/16"-24 | 0.2719 in | I (0.2720 in) | 75% |
| 3/8"-16 | 0.3141 in | 5/16" (0.3125 in) | 77% |
| 3/8"-24 | 0.3344 in | Q (0.3320 in) | 79% |
| 1/2"-13 | 0.4251 in | 27/64" (0.4219 in) | 78% |
| 1/2"-20 | 0.4513 in | 29/64" (0.4531 in) | 72% |
| M3x0.5 | 2.513 mm | 2.5 mm | 77% |
| M4x0.7 | 3.318 mm | 3.3 mm | 77% |
| M5x0.8 | 4.221 mm | 4.2 mm | 77% |
| M6x1 | 5.026 mm | 5 mm | 77% |
| M8x1.25 | 6.782 mm | 6.8 mm | 74% |
| M10x1.5 | 8.539 mm | 8.5 mm | 77% |
| M12x1.75 | 10.295 mm | 10.2 mm | 79% |
Inch threads: the nearest standard drill. Metric threads: the ISO 2306 / DIN 336 tap drill. Cut taps only; form taps need larger holes. Any other thread: tap drill calculator.