Metric SHCS Hole & Counterbore Sizes
| Nominal Screw Size | Clearance Hole Dia. mm | Counterbore Dia. mm | Countersink Dia. mm | Tapping Drill mm | ||
| Close | Normal | ISO | M Fine | |||
| M3 | 3.4 | 3.7 | 6.5 | 3.6 | 0.5 | – |
| M4 | 4.4 | 4.8 | 8.25 | 4.7 | 0.7 | – |
| M5 | 5.4 | 5.8 | 9.75 | 5.7 | 4.2 | – |
| M6 | 6.4 | 6.8 | 11.25 | 6.8 | 5.0 | – |
| M8 | 8.4 | 8.8 | 14.25 | 9.2 | 6.8 | 7.0 |
| M10 | 10.5 | 10.8 | 17.25 | 11.2 | 8.5 | 8.8 |
| M12 | 12.5 | 12.8 | 19.25 | 14.2 | 10.2 | 10.5 |
| M14 | 14.5 | 14.75 | 22.25 | 16.2 | 12.0 | 12.5 |
| M16 | 16.5 | 16.75 | 25.5 | 18.2 | 14.0 | 14.5 |
| M20 | 20.5 | 20.75 | 31.5 | 22.4 | 17.5 | 18.5 |
| M24 | 24.5 | 24.75 | 37.5 | 26.4 | 21.0 | 22.0 |
| M30 | 30.75 | 31.75 | 47.5 | 33.4 | 26.5 | – |
Imperial SHCS Hole & Counterbore Sizes
| Nominal Screw Size | Clearance Hole Dia. mm | Counterbore Dia. mm | Countersink Dia. mm | Tapping Drill mm | ||
| Close | Normal | UNF | UNC | |||
| 8 | 4.6 | 5.0 | 8.0 | 4.8 | 3.5 | 3.4 |
| 10 | 5.2 | 5.6 | 9.5 | 5.5 | 4.1 | 3.8 |
| 1/4″ | 6.8 | 7.2 | 11.0 | 7.0 | 5.5 | 5.1 |
| 5/16″ | 8.4 | 8.8 | 13.5 | 8.8 | 6.9 | 6.6 |
| 3/8″ | 10.0 | 10.4 | 16.0 | 10.5 | 8.5 | 8.0 |
| 7/16″ | 11.5 | 12.0 | 18.0 | 12.2 | 9.8 | 9.4 |
| 1/2″ | 13.0 | 13.5 | 20.5 | 14.0 | 11.5 | 10.8 |
| 5/8″ | 16.2 | 16.8 | 25.5 | 17.5 | 14.5 | 13.5 |
| 3/4″ | 19.5 | 19.8 | 30.0 | 21.0 | 17.5 | 16.5 |
| 7/8″ | 22.8 | 23.0 | 35.0 | 24.5 | 20.5 | 19.5 |
| 1″ | 25.8 | 26.2 | 41.0 | 28.0 | 23.5 | 22.0 |
| 1 1/4″ | 32.6 | 33.4 | 50 | 35 | 29.5 | 28.0 |
