Drill Bit Sizes Reference
Comprehensive chart for fractional, metric, and letter drill bit sizes.
| Size (Fractional) | Decimal (inch) | Metric (mm) |
|---|---|---|
| 1/16 | 0.0625" | 1.588 mm |
| 5/64 | 0.0781" | 1.984 mm |
| 3/32 | 0.0938" | 2.381 mm |
| 7/64 | 0.1094" | 2.778 mm |
| 1/8 | 0.1250" | 3.175 mm |
| 9/64 | 0.1406" | 3.572 mm |
| 5/32 | 0.1563" | 3.969 mm |
| 11/64 | 0.1719" | 4.366 mm |
| 3/16 | 0.1875" | 4.763 mm |
| 13/64 | 0.2031" | 5.159 mm |
| 7/32 | 0.2188" | 5.556 mm |
| 15/64 | 0.2344" | 5.953 mm |
| 1/4 | 0.2500" | 6.350 mm |
| 5/16 | 0.3125" | 7.938 mm |
| 3/8 | 0.3750" | 9.525 mm |
| 7/16 | 0.4375" | 11.113 mm |
| 1/2 | 0.5000" | 12.700 mm |
Tap & Drill
When drilling for a tap, the drill size must be slightly smaller than the tap diameter. Always check a specific tap-drill chart for your specific thread pitch.
Material Clearance
For a loose fit (clearance hole), use a drill bit one size larger than the nominal bolt or screw diameter.
Cite this page
UnitConvertLab. (2026). Drill Bit Sizes Reference. UnitConvertLab. Retrieved from https://unitconvertlab.com/reference/drill-bits