Workshop reference
Drill Size Comparison Chart
A quick comparison of common fractional, number, letter, and metric drill sizes.
| Size | Decimal inch | Millimeters |
|---|---|---|
| #60 | 0.0400 | 1.016 |
| #50 | 0.0700 | 1.778 |
| #40 | 0.0980 | 2.489 |
| 1/8 | 0.1250 | 3.175 |
| #30 | 0.1285 | 3.264 |
| 9/64 | 0.1406 | 3.572 |
| 5/32 | 0.1563 | 3.969 |
| 3/16 | 0.1875 | 4.763 |
| 1/4 | 0.2500 | 6.350 |
| 5/16 | 0.3125 | 7.938 |
| 3/8 | 0.3750 | 9.525 |
| 1/2 | 0.5000 | 12.700 |
This is a comparison chart, not a tap drill or clearance hole specification. Choose a drill for the actual fastener, thread, fit, and material.
Use the chart as a starting point
Reference values help compare sizes and plan a job. Product specifications, codes, tolerances, and the actual material still control the final choice.