All drill sizes are in mm.
| BA number | threads per inch | Tapping drill size | Clearance drill size |
|---|---|---|---|
| 0 | 25.40 | 5.2 | 6.1 |
| 1 | 28.22 | 4.5 | 5.4 |
| 2 | 31.35 | 4.1 | 4.8 |
| 3 | 34.79 | 3.5 | 4.2 |
| 4 | 38.48 | 3.0 | 3.7 |
| 5 | 43.05 | 2.65 | 3.3 |
| 6 | 47.92 | 2.3 | 2.85 |
| 7 | 52.91 | 2.1 | 2.55 |
| 8 | 59.07 | 1.8 | 2.3 |
| 9 | 65.12 | 1.6 | 1.95 |
| 10 | 72.57 | 1.4 | 1.75 |
| 11 | 81.93 | 1.2 | 1.5 |
| 12 | 90.71 | 1.05 | 1.3 |
| 13 | 101.60 | 0.975 | 1.15 |
| 14 | 110.43 | 0.80 | 1.00 |
| 15 | 120.95 | 0.70 | 0.90 |
| 16 | 133.68 | 0.60 | 0.80 |