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Metric clearance hole chart (ISO 273)
Medium fit is the everyday choice. Use fine (close) fit for location, and coarse fit when the holes in mating parts may not line up perfectly.
| Bolt | Fine (mm) | Medium (mm) | Coarse (mm) | Tap drill (coarse) |
|---|---|---|---|---|
| M1.6 | 1.7 | 1.8 | 2 | 1.25 mm |
| M2 | 2.2 | 2.4 | 2.6 | 1.6 mm |
| M2.5 | 2.7 | 2.9 | 3.1 | 2.05 mm |
| M3 | 3.2 | 3.4 | 3.6 | 2.5 mm |
| M3.5 | 3.7 | 3.9 | 4.2 | 2.9 mm |
| M4 | 4.3 | 4.5 | 4.8 | 3.3 mm |
| M5 | 5.3 | 5.5 | 5.8 | 4.2 mm |
| M6 | 6.4 | 6.6 | 7 | 5 mm |
| M8 | 8.4 | 9 | 10 | 6.8 mm |
| M10 | 10.5 | 11 | 12 | 8.5 mm |
| M12 | 13 | 13.5 | 14.5 | 10.2 mm |
| M14 | 15 | 15.5 | 16.5 | 12 mm |
| M16 | 17 | 17.5 | 18.5 | 14 mm |
| M18 | 19 | 20 | 21 | 15.5 mm |
| M20 | 21 | 22 | 24 | 17.5 mm |
| M22 | 23 | 24 | 26 | 19.5 mm |
| M24 | 25 | 26 | 28 | 21 mm |
| M27 | 28 | 30 | 32 | 24 mm |
| M30 | 31 | 33 | 35 | 26.5 mm |