Bolt/Screw Hole Size Table
Very useful information for making PCBs or drilling mounting holes of some sort. Sizes are in inches. For example, a 4-40 bolt is 0.112 inches, or 112 mils in diameter. If you're drilling a hole to comfortably pass the bolt through, make it 123 mils.
| Bolt Number | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 8 | 10 | 12 |
| Diameter | 0.060 | 0.073 | 0.086 | 0.099 | 0.112 | 0.125 | 0.138 | 0.164 | 0.190 | 0.216 |
| Hole Diameter | 0.066 | 0.080 | 0.095 | 0.109 | 0.123 | 0.138 | 0.152 | 0.180 | 0.209 |
0.238 |
Drill Bit Sizing Chart
For standard 1/64" drill bit sizes. This table gives the decimal equivalent of the fractional bit sizes along with their diameter in millimeters. Following the same example, a hole for a 4-40 bolt (0.123 inches) would need a 1/8" drill bit.
| Bit Size | Decimal Inches | mm |
| 1/64 | 0.016 | 0.397 |
| 1/32 | 0.031 | 0.794 |
| 3/64 | 0.047 | 1.191 |
| 1/16 | 0.063 | 1.588 |
| 5/64 | 0.078 | 1.984 |
| 3/32 | 0.094 | 2.381 |
| 7/64 | 0.109 | 2.778 |
| 1/8 | 0.125 | 3.175 |
| 9/64 | 0.141 | 3.572 |
| 5/32 | 0.156 | 3.969 |
| 11/64 | 0.172 | 4.366 |
| 3/16 | 0.188 | 4.763 |
| 13/64 | 0.203 | 5.159 |
| 7/32 | 0.219 | 5.556 |
| 15/64 | 0.234 | 5.953 |
| 1/4 | 0.250 | 6.350 |
| 17/64 | 0.266 | 6.747 |
| 9/32 | 0.281 | 7.144 |
| 19/64 | 0.297 | 7.541 |
| 5/16 | 0.313 | 7.938 |
| 21/64 | 0.328 | 8.334 |
| 11/32 | 0.344 | 8.731 |
| 23/64 | 0.359 | 9.128 |
| 3/8 | 0.375 | 9.525 |
| 25/64 | 0.391 | 9.922 |
| 13/32 | 0.406 | 10.319 |
| 27/64 | 0.422 | 10.716 |
| 7/16 | 0.438 | 11.113 |
| 29/64 | 0.453 | 11.509 |
| 15/32 | 0.469 | 11.906 |
| 31/64 | 0.484 | 12.303 |
| 1/2 | 0.500 | 12.700 |
| 33/64 | 0.516 | 13.097 |
| 17/32 | 0.531 | 13.494 |
| 35/64 | 0.547 | 13.891 |
| 9/16 | 0.563 | 14.288 |
| 37/64 | 0.578 | 14.684 |
| 19/32 | 0.594 | 15.081 |
| 39/64 | 0.609 | 15.478 |
| 5/8 | 0.625 | 15.875 |
| 41/64 | 0.641 | 16.272 |
| 21/32 | 0.656 | 16.669 |
| 43/64 | 0.672 | 17.066 |
| 11/16 | 0.688 | 17.463 |
| 45/64 | 0.703 | 17.859 |
| 23/32 | 0.719 | 18.256 |
| 47/64 | 0.734 | 18.653 |
| 3/4 | 0.750 | 19.050 |
Note: Feel free to copy this information. It's pretty generic stuff that nobody can actually claim copyrights over - the easier it is to find, the better. The bolt table was made using a formula found here, although I'm sure it's available elsewhere.
