Clearance Holes
Through-hole diameters for screws and bolts at close, normal, and loose fits.
Clearance holes let a fastener pass freely through a part. Pick close for precise alignment, normal for general assembly, or loose where parts must shift to line up.
Inch (ASME B18.2.8)
| Size | Close (in) | Normal (in) | Loose (in) |
|---|---|---|---|
| #0 | 0.067 | 0.076 | 0.094 |
| #1 | 0.081 | 0.089 | 0.104 |
| #2 | 0.094 | 0.102 | 0.116 |
| #3 | 0.106 | 0.116 | 0.128 |
| #4 | 0.120 | 0.128 | 0.144 |
| #5 | 0.141 | 0.156 | 0.172 |
| #6 | 0.154 | 0.170 | 0.185 |
| #8 | 0.180 | 0.196 | 0.213 |
| #10 | 0.206 | 0.221 | 0.238 |
| 1/4 | 0.266 | 0.281 | 0.297 |
| 5/16 | 0.328 | 0.344 | 0.359 |
| 3/8 | 0.391 | 0.406 | 0.422 |
| 7/16 | 0.453 | 0.469 | 0.484 |
| 1/2 | 0.531 | 0.562 | 0.609 |
| 5/8 | 0.656 | 0.688 | 0.734 |
| 3/4 | 0.781 | 0.812 | 0.906 |
| 7/8 | 0.906 | 0.938 | 1.031 |
| 1 | 1.031 | 1.094 | 1.156 |
Metric (ISO 273)
| Size | Fine (mm) | Medium (mm) | Coarse (mm) |
|---|---|---|---|
| M1.6 | 1.7 | 1.8 | 2.0 |
| M2 | 2.2 | 2.4 | 2.6 |
| M2.5 | 2.7 | 2.9 | 3.1 |
| M3 | 3.2 | 3.4 | 3.6 |
| M4 | 4.3 | 4.5 | 4.8 |
| M5 | 5.3 | 5.5 | 5.8 |
| M6 | 6.4 | 6.6 | 7.0 |
| M8 | 8.4 | 9.0 | 10.0 |
| M10 | 10.5 | 11.0 | 12.0 |
| M12 | 13.0 | 13.5 | 14.5 |
| M16 | 17.0 | 17.5 | 18.5 |
| M20 | 21.0 | 22.0 | 24.0 |