Recommended Tapping Drill and Clearance Hole Sizes
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Use these tables for calculating the relevant size drill bit and clearance hole for ISO metric coarse and fine threads.
All dimensions are in millimeters (mm).
| Clearance Hole Size | |||||
| Nominal Size | Thread Pitch | Tapping Drill Size | Close Fit | Medium Fit | Free Fit |
| M1 | 0.25 | 0.75 | - | 1.2 | - |
| M1.1 | 0.25 | 0.85 | - | - | - |
| M1.2 | 0.25 | 0.95 | - | 1.4 | - |
| M1.4 | 0.3 | 1.1 | - | 1.6 | - |
| M1.6 | 0.35 | 1.25 | 1.7 | 1.8 | 2 |
| M1.8 | 0.35 | 1.45 | - | 2 | - |
| M2 | 0.4 | 1.6 | 2.2 | 2.4 | 2.6 |
| M2.2 | 0.45 | 1.75 | - | 2.8 | - |
| M2.5 | 0.45 | 2.05 | 2.7 | 2.9 | 3.1 |
| M3 | 0.5 | 2.5 | 3.2 | 3.4 | 3.6 |
| M3.5 | 0.6 | 2.9 | - | 3.9 | - |
| M4 | 0.7 | 3.3 | 4.3 | 4.5 | 4.8 |
| M4.5 | 0.75 | 3.75 | - | - | - |
| M5 | 0.8 | 4.2 | 5.3 | 5.5 | 5.8 |
| M6 | 1 | 5 | 6.4 | 6.6 | 7 |
| M7 | 1 | 6 | - | - | - |
| M8 | 1.25 | 6.75 | 8.4 | 9 | 10 |
| M9 | 1.25 | 7.75 | - | - | - |
| M10 | 1.5 | 8.5 | 10.5 | 11 | 12 |
| M11 | 1.5 | 9.5 | - | - | - |
| M12 | 1.75 | 10.2 | 13 | 14 | 15 |
| M14 | 2 | 12 | 15 | 16 | 17 |
| M16 | 2 | 14 | 17 | 18 | 19 |
| M18 | 2.5 | 15.5 | 19 | 20 | 21 |
| M20 | 2.5 | 17.5 | 21 | 22 | 24 |
| M22 | 2.5 | 19.5 | 23 | 24 | 26 |
| M24 | 3 | 21 | 25 | 26 | 28 |
| M27 | 3 | 24 | 28 | 30 | 32 |
| M30 | 3.5 | 26.5 | 31 | 33 | 35 |
| M33 | 3.5 | 29.5 | 34 | 36 | 38 |
| M36 | 4 | 32 | 37 | 39 | 42 |
| M39 | 4 | 35 | 40 | 42 | 45 |
| M42 | 4.5 | 37.5 | 43 | 45 | 48 |
| M45 | 4.5 | 40.5 | 46 | 48 | 52 |
| M48 | 5 | 43 | 50 | 52 | 56 |
| M52 | 5 | 47 | 54 | 56 | 62 |
| M56 | 5.5 | 50.5 | - | - | - |
| M60 | 5.5 | 54.5 | - | - | - |
| M64 | 6 | 58 | - | - | - |
| M68 | 6 | 62 | - | - | - |
| M72 | 6 | 66 | - | - | - |
| M76 | 6 | 70 | - | - | - |
| Size | Pitch | Drill |
|---|---|---|
| M2 | 0.25 | 1.75 |
| M2.2 | 0.25 | 1.95 |
| M2.3 | 0.25 | 2.05 |
| M2.5 | 0.35 | 2.15 |
| M2.6 | 0.35 | 2.25 |
| M3 | 0.35 | 2.65 |
| M3.5 | 0.35 | 3.15 |
| M4 | 0.35 | 3.65 |
| M4 | 0.5 | 3.5 |
| M5 | 0.35 | 4.65 |
| M5 | 0.5 | 4.5 |
| M5 | 0.75 | 4.25 |
| M5.5 | 0.5 | 5 |
| M6 | 0.5 | 5.5 |
| M6 | 0.75 | 5.25 |
| M7 | 0.75 | 6.25 |
| M8 | 0.5 | 7.5 |
| M8 | 0.75 | 7.25 |
| M8 | 1 | 7 |
| M9 | 0.75 | 8.25 |
| M9 | 1 | 8 |
| M10 | 0.5 | 9.5 |
| M10 | 0.75 | 9.25 |
| M10 | 1 | 9 |
| M10 | 1.25 | 8.75 |
| M11 | 0.75 | 10.25 |
| M11 | 1 | 10 |
| M11 | 1.25 | 9.75 |
| M12 | 0.5 | 11.5 |
| M12 | 0.75 | 11.25 |
| M12 | 1 | 11 |
| M12 | 1.25 | 10.75 |
| M12 | 1.5 | 10.5 |
| M14 | 1 | 13 |
| M14 | 1.25 | 12.75 |
| M14 | 1.5 | 12.5 |
| M15 | 0.75 | 14.25 |
| M15 | 1 | 14 |
| M15 | 1.5 | 13.5 |
| M16 | 0.5 | 15.5 |
| M16 | 0.75 | 15.25 |
| M16 | 1 | 15 |
| M16 | 1.25 | 14.75 |
| M16 | 1.5 | 14.5 |
| M17 | 1 | 16 |
| M17 | 1.5 | 15.5 |
| M18 | 0.75 | 17.25 |
| M18 | 1 | 17 |
| M18 | 1.25 | 16.75 |
| M18 | 1.5 | 16.5 |
| M18 | 2 | 16 |
| M19 | 1 | 18 |
| M20 | 1.5 | 18.5 |
| M20 | 2 | 18 |
| M22 | 1 | 21 |
| M22 | 1.5 | 20.5 |
| M22 | 2 | 20 |
| M24 | 1 | 23 |
| M24 | 1.5 | 22.5 |
| M24 | 2 | 22 |
| M25 | 1 | 24 |
| M25 | 1.5 | 23.5 |
| M25 | 2 | 23 |
| M27 | 1 | 26 |
| M27 | 1.5 | 25.5 |
| M27 | 2 | 25 |
| M28 | 1 | 27 |
| M28 | 1.5 | 26.5 |
| M28 | 2 | 26 |
| M30 | 1 | 29 |
| M30 | 1.5 | 28.5 |
| M30 | 2 | 28 |
| M30 | 3 | 27 |
| M32 | 1 | 31 |
| M32 | 1.5 | 30.5 |
| M32 | 2 | 30 |
| M33 | 1.5 | 31.5 |
| M33 | 2 | 31 |
| M33 | 3 | 30 |
| M35 | 1.5 | 33.5 |
| M35 | 2 | 33 |
| M35 | 3 | 32 |
| M36 | 1 | 35 |
| M36 | 1.5 | 34.4 |
| M36 | 2 | 34 |
| M36 | 3 | 33 |
| M38 | 1 | 37 |
| M38 | 1.5 | 36.5 |
| M38 | 2 | 36 |
| M39 | 1.5 | 37.5 |
| M39 | 2 | 37 |
| M39 | 3 | 36 |
| M40 | 1 | 39 |
| M40 | 1.5 | 38.5 |
| M40 | 3 | 37 |
| M42 | 1.5 | 40.5 |
| M42 | 2 | 40 |
| M42 | 3 | 39 |
| M42 | 4 | 38 |
| M45 | 1.5 | 43.5 |
| M45 | 2 | 43 |
| M45 | 3 | 42 |
| M48 | 1.5 | 46.5 |
| M48 | 2 | 46 |
| M48 | 3 | 45 |
| M48 | 4 | 44 |
| M50 | 1.5 | 48.5 |
| M50 | 2 | 48 |
| M50 | 3 | 47 |
| M52 | 1.5 | 50.5 |
| M52 | 2 | 50 |
| M52 | 3 | 49 |
| M52 | 4 | 48 |
| M56 | 2 | 54 |
| M56 | 4 | 52 |