Metric Threads - Clearance Holes and Tapping Drill Sizes
Recommended clearance holes and drill tap sizes.
Clearance holes for metric bolts:
| Size Nominal Diameter (mm) | Pitch (mm) | Clearance Hole (mm) | Tap Drill Standard Pitch (mm) | ||
|---|---|---|---|---|---|
| Fine | Medium | Coarse | |||
| 1.6 | 0.35 | 1.7 | 1.8 | 2 | |
| 1.8 | 0.35 | 2.0 | |||
| 2 | 0.40 | 2.2 | 2.25 | 2.6 | |
| 2.2 | 0.45 | 2.45 | |||
| 2.5 | 0.45 | 2.7 | 2.8 | 3.1 | |
| 3 | 0.50 | 3.2 | 3.35 | 3.6 | |
| 3.5 | 0.60 | 3.9 | |||
| 4 | 0.70 | 4.3 | 4.5 | 4.8 | |
| 4.5 | 0.75 | 5.0 | |||
| 5 | 0.80 | 5.3 | 5.5 | 5.8 | 4.2 |
| 6 | 1.00 | 6.4 | 6.5 | 7 | 5 |
| 7 | 1.00 | 7.4 | 7.8 | 8 | |
| 8 | 1.25 | 8.4 | 9 | 10 | 6.75 |
| 10 | 1.50 | 10.5 | 11 | 12 | 8.5 |
| 12 | 1.75 | 13 | 14 | 15 | 10.25 |
| 16 | 2.0 | 17 | 18 | 19 | 14 |
| 20 | 2.5 | 21 | 22 | 24 | 17.5 |
| 24 | 3.0 | 25 | 26 | 28 | 21 |
| 30 | 3.5 | 31 | 32 | 35 | 26.5 |
- Nominal diameters according ISO 724 - Metric Threads.
