🔩 Drill Bit Sizes Reference
Drill bits are available in fractional inch, letter (A–Z), number (1–80), and metric sizes. Use this chart to find inch and millimeter equivalents for any drill bit system.
Fractional Inch
| Size | Inches | mm |
|---|---|---|
| 1/64" | 0.0156 | 0.397 |
| 1/32" | 0.0313 | 0.794 |
| 3/64" | 0.0469 | 1.191 |
| 1/16" | 0.0625 | 1.588 |
| 5/64" | 0.0781 | 1.984 |
| 3/32" | 0.0938 | 2.381 |
| 7/64" | 0.1094 | 2.778 |
| 1/8" | 0.1250 | 3.175 |
| 9/64" | 0.1406 | 3.572 |
| 5/32" | 0.1563 | 3.969 |
| 3/16" | 0.1875 | 4.763 |
| 7/32" | 0.2188 | 5.556 |
| 1/4" | 0.2500 | 6.350 |
| 9/32" | 0.2813 | 7.144 |
| 5/16" | 0.3125 | 7.938 |
| 3/8" | 0.3750 | 9.525 |
| 7/16" | 0.4375 | 11.113 |
| 1/2" | 0.5000 | 12.700 |
Letter Sizes (A–Z)
| Size | Inches | mm |
|---|---|---|
| A | 0.2340 | 5.944 |
| B | 0.2380 | 6.045 |
| C | 0.2420 | 6.147 |
| D | 0.2460 | 6.248 |
| E | 0.2500 | 6.350 |
| F | 0.2570 | 6.528 |
| G | 0.2610 | 6.629 |
| H | 0.2660 | 6.756 |
| I | 0.2720 | 6.909 |
| J | 0.2770 | 7.036 |
| K | 0.2810 | 7.137 |
| L | 0.2900 | 7.366 |
| M | 0.2950 | 7.493 |
| N | 0.3020 | 7.671 |
| O | 0.3160 | 8.026 |
| P | 0.3230 | 8.204 |
| Q | 0.3320 | 8.433 |
| R | 0.3390 | 8.611 |
| S | 0.3480 | 8.839 |
| T | 0.3580 | 9.093 |
| U | 0.3680 | 9.347 |
| V | 0.3770 | 9.576 |
| W | 0.3860 | 9.804 |
| X | 0.3970 | 10.084 |
| Y | 0.4040 | 10.262 |
| Z | 0.4130 | 10.490 |
Metric Sizes
| Size | Inches |
|---|---|
| 0.5 mm | 0.0197 |
| 0.8 mm | 0.0315 |
| 1.0 mm | 0.0394 |
| 1.5 mm | 0.0591 |
| 2.0 mm | 0.0787 |
| 2.5 mm | 0.0984 |
| 3.0 mm | 0.1181 |
| 3.5 mm | 0.1378 |
| 4.0 mm | 0.1575 |
| 4.5 mm | 0.1772 |
| 5.0 mm | 0.1969 |
| 6.0 mm | 0.2362 |
| 6.5 mm | 0.2559 |
| 7.0 mm | 0.2756 |
| 8.0 mm | 0.3150 |
| 9.0 mm | 0.3543 |
| 10.0 mm | 0.3937 |
| 12.0 mm | 0.4724 |