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Printable tap drill chart
Inch and metric tap drills on one sheet for the shop wall. Use your browser's print dialog and pick "Save as PDF" for a PDF copy. Drills give about 75% thread (inch, ASME B1.1) or follow major diameter minus pitch (ISO metric).
Inch: UNC and UNF
| Thread | Drill | Decimal | mm | % thr. |
|---|---|---|---|---|
| #0-80 UNF | 3/64 | 0.0469 | 1.19 | 81% |
| #1-64 UNC | #53 | 0.0595 | 1.51 | 67% |
| #1-72 UNF | #53 | 0.0595 | 1.51 | 75% |
| #2-56 UNC | #50 | 0.0700 | 1.78 | 69% |
| #2-64 UNF | #50 | 0.0700 | 1.78 | 79% |
| #3-48 UNC | #47 | 0.0785 | 1.99 | 76% |
| #3-56 UNF | #45 | 0.0820 | 2.08 | 73% |
| #4-40 UNC | #43 | 0.0890 | 2.26 | 71% |
| #4-48 UNF | #42 | 0.0935 | 2.38 | 68% |
| #5-40 UNC | #38 | 0.1015 | 2.58 | 72% |
| #5-44 UNF | #37 | 0.1040 | 2.64 | 71% |
| #6-32 UNC | #36 | 0.1065 | 2.71 | 78% |
| #6-40 UNF | #33 | 0.1130 | 2.87 | 77% |
| #8-32 UNC | #29 | 0.1360 | 3.45 | 69% |
| #8-36 UNF | #29 | 0.1360 | 3.45 | 78% |
| #10-24 UNC | #25 | 0.1495 | 3.80 | 75% |
| #10-32 UNF | #21 | 0.1590 | 4.04 | 76% |
| #12-24 UNC | #16 | 0.1770 | 4.50 | 72% |
| #12-28 UNF | #14 | 0.1820 | 4.62 | 73% |
| 1/4-20 UNC | #7 | 0.2010 | 5.11 | 75% |
| 1/4-28 UNF | #3 | 0.2130 | 5.41 | 80% |
| 5/16-18 UNC | F | 0.2570 | 6.53 | 77% |
| 5/16-24 UNF | I | 0.2720 | 6.91 | 75% |
| 3/8-16 UNC | 5/16 | 0.3125 | 7.94 | 77% |
| 3/8-24 UNF | Q | 0.3320 | 8.43 | 79% |
| 7/16-14 UNC | U | 0.3680 | 9.35 | 75% |
| 7/16-20 UNF | 25/64 | 0.3906 | 9.92 | 72% |
| 1/2-13 UNC | 27/64 | 0.4219 | 10.72 | 78% |
| 1/2-20 UNF | 29/64 | 0.4531 | 11.51 | 72% |
| 9/16-12 UNC | 31/64 | 0.4844 | 12.30 | 72% |
| 9/16-18 UNF | 33/64 | 0.5156 | 13.10 | 65% |
| 5/8-11 UNC | 17/32 | 0.5313 | 13.49 | 79% |
| 5/8-18 UNF | 37/64 | 0.5781 | 14.68 | 65% |
| 3/4-10 UNC | 21/32 | 0.6563 | 16.67 | 72% |
| 3/4-16 UNF | 11/16 | 0.6875 | 17.46 | 77% |
| 7/8-9 UNC | 49/64 | 0.7656 | 19.45 | 76% |
| 7/8-14 UNF | 13/16 | 0.8125 | 20.64 | 67% |
| 1-8 UNC | 7/8 | 0.8750 | 22.23 | 77% |
| 1-12 UNF | 59/64 | 0.9219 | 23.42 | 72% |
Metric: ISO coarse and fine
| Thread | Drill (mm) | Inch alt. |
|---|---|---|
| M1.6 x 0.35 | 1.25 | 3/64 |
| M2 x 0.4 | 1.6 | #52 |
| M2.5 x 0.45 | 2.05 | #46 |
| M3 x 0.5 | 2.5 | #40 |
| M3.5 x 0.6 | 2.9 | #33 |
| M4 x 0.7 | 3.3 | #30 |
| M5 x 0.8 | 4.2 | #19 |
| M6 x 1 | 5 | #9 |
| M8 x 1.25 | 6.8 | H |
| M10 x 1.5 | 8.5 | Q |
| M12 x 1.75 | 10.2 | Y |
| M14 x 2 | 12 | 15/32 |
| M16 x 2 | 14 | 35/64 |
| M18 x 2.5 | 15.5 | 39/64 |
| M20 x 2.5 | 17.5 | 11/16 |
| M22 x 2.5 | 19.5 | 49/64 |
| M24 x 3 | 21 | 53/64 |
| M27 x 3 | 24 | 15/16 |
| M30 x 3.5 | 26.5 | 1 in |
| M8 x 1 | 7 | J |
| M10 x 1.25 | 8.8 | S |
| M10 x 1 | 9 | T |
| M12 x 1.5 | 10.5 | Z |
| M12 x 1.25 | 10.8 | 27/64 |
| M14 x 1.5 | 12.5 | 31/64 |
| M16 x 1.5 | 14.5 | 37/64 |
| M18 x 1.5 | 16.5 | 21/32 |
| M20 x 1.5 | 18.5 | 47/64 |
| M22 x 1.5 | 20.5 | 13/16 |
| M24 x 2 | 22 | 55/64 |
Source: calculated from ASME B1.1 and ISO 261 thread dimensions. tapdrill.pages.dev
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Frequently asked questions
Can I download this tap drill chart as a PDF?
Yes. Click Print and choose Save as PDF as the printer. The page is formatted to print cleanly without menus.
Why does the metric column not show % of thread?
ISO practice is to drill at major diameter minus pitch, which gives roughly 75–77% thread for every size, so one rule covers the whole column.
Can I share this chart?
Yes, print it for your shop or class. If you post it online, please link back to this page.