When drilling and tapping a hole you need to drill your workpiece to the right size and in order to tap your workpiece to the correct size. Below is a Metric drill and tap chart for 75% thread. You can find an SAE drill and tap chart here. You can also find an article on how to drill and tap a hole properly here.
| Tap Size (mm) | Thread Pitch (mm) | Drill Size (mm) | Closest Drill size (in.) |
|---|---|---|---|
| M1.5 | 0.35 | 1.15 | 56 |
| M1.6 | 0.35 | 1.25 | 55 |
| M1.8 | 0.35 | 1.45 | 53 |
| M2 | 0.45 | 1.55 | 1/16 |
| 0.40 | 1.60 | 52 | |
| M2.2 | 0.45 | 1.75 | 50 |
| M2.5 | 0.45 | 2.05 | 46 |
| M3 | 0.60 | 2.40 | 41 |
| 0.50 | 2.50 | 39 | |
| M3.5 | 0.60 | 2.90 | 32 |
| M4 | 0.75 | 3.25 | 30 |
| 0.70 | 3.30 | 30 | |
| M4.5 | 0.75 | 3.75 | 25 |
| M5 | 1.00 | 4.00 | 21 |
| 0.90 | 4.10 | 20 | |
| 0.80 | 4.20 | 19 | |
| M5.5 | 0.90 | 4.60 | 14 |
| M6 | 1.00 | 5.00 | 8 |
| 0.75 | 5.25 | 4 | |
| M7 | 1.00 | 6.00 | 8 |
| 0.75 | 6.25 | D | |
| M8 | 1.25 | 6.80 | H |
| 1.00 | 7.00 | J | |
| M9 | 1.25 | 7.80 | N |
| 1.00 | 8.00 | O | |
| M10 | 1.50 | 8.30 | R |
| 1.25 | 8.80 | 11/32 | |
| 1.00 | 9.00 | T | |
| M11 | 1.50 | 9.50 | 3/8 |
| M12 | 1.75 | 10.30 | 13/32 |
| 1.50 | 10.50 | 2 | |
| 1.25 | 10.80 | 27/64 | |
| M14 | 2.00 | 12.10 | 15/32 |
| 1.50 | 12.50 | 1/2 | |
| 1.25 | 12.80 | 1/2 | |
| M15 | 1.30 | 13.80 | 17/32 |
| M16 | 2.00 | 14.00 | 35/64 |
| 1.50 | 14.50 | 37/64 | |
| M17 | 1.50 | 15.50 | 39/64 |
| M18 | 1.00 | 15.50 | 39/64 |
| 1.50 | 16.00 | 5/8 | |
| 1.75 | 16.50 | 21/32 | |
| 2.50 | 15.00 | 39/64 | |
| M19 | 1.5 | 16.50 | 21/32 |
| M20 | 1.25 | 17.50 | 11/16 |
| 1.50 | 18.50 | 47/64 | |
| 2.00 | 18.00 | 45/64 | |
| 2.50 | 17.00 | 43/64 |