Convert a drill size between a fraction (e.g. 7/32), decimal inches, and millimetres. Type any value into one field — the others update instantly. The reference table below covers the number, letter and fraction drills used elsewhere on this site for tap-drill and clearance holes.
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Converter
in
mm
Named drill size reference (number, letter, fraction)
| Drill | Decimal inch | Millimetres |
|---|---|---|
| #50 | 0.0700″ | 1.78 mm |
| #47 | 0.0785″ | 1.99 mm |
| #45 | 0.0820″ | 2.08 mm |
| #43 | 0.0890″ | 2.26 mm |
| #42 | 0.0935″ | 2.37 mm |
| #38 | 0.1015″ | 2.58 mm |
| #37 | 0.1040″ | 2.64 mm |
| #36 | 0.1065″ | 2.71 mm |
| #33 | 0.1130″ | 2.87 mm |
| #29 | 0.1360″ | 3.45 mm |
| #25 | 0.1495″ | 3.8 mm |
| #21 | 0.1590″ | 4.04 mm |
| #16 | 0.1770″ | 4.5 mm |
| #14 | 0.1820″ | 4.62 mm |
| #7 | 0.2010″ | 5.11 mm |
| #3 | 0.2130″ | 5.41 mm |
| F | 0.2570″ | 6.53 mm |
| I | 0.2720″ | 6.91 mm |
| 5/16 | 0.3125″ | 7.94 mm |
| Q | 0.3320″ | 8.43 mm |
| U | 0.3680″ | 9.35 mm |
| 25/64 | 0.3906″ | 9.92 mm |
| 27/64 | 0.4219″ | 10.72 mm |
| 29/64 | 0.4531″ | 11.51 mm |
| 31/64 | 0.4844″ | 12.3 mm |
| 33/64 | 0.5156″ | 13.1 mm |
| 17/32 | 0.5312″ | 13.49 mm |
| 37/64 | 0.5781″ | 14.68 mm |
| 21/32 | 0.6562″ | 16.67 mm |
| 11/16 | 0.6875″ | 17.46 mm |
| 49/64 | 0.7656″ | 19.45 mm |
| 13/16 | 0.8125″ | 20.64 mm |
| 7/8 | 0.8750″ | 22.22 mm |
| 59/64 | 0.9219″ | 23.42 mm |
| 63/64 | 0.9844″ | 25.0 mm |
More standards, diameters and pitches in the mobile app
GET IT ONGoogle Play