| Size | Decimal (in) | Metric (mm) | Closest Frac | Common Use |
|---|
Number Drills: #80 (smallest) to #1 (largest). Higher numbers = smaller diameter.
Letter Drills: A (smallest) to Z (largest). Common for tap drilling.
Fractional: Standard fractions from 1/64" up. Most common in general machining.
Metric: Decimal millimeter sizes. Standard in most of the world.
End Mills: Common sizes for milling operations with typical shank configurations.
Wire Gauge: AWG sizes useful for clearance holes for electrical components.