🔩 Drill Bit Size Chart

Number, letter, fractional & metric drill bit sizes — inches and millimeters, side by side.

Number (#1-#80)
Letter (A-Z)
Fractional
Metric
SizeInchesmm

Detailed view of woodworking drill bits on a wooden surface in a workshop environment.

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Drill Bit Sizing Guide

A row of cordless power drills on a wooden workbench, ready for use.

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Number Drills (#1–#80)

Sized from largest (#1 = 0.2280") to smallest (#80 = 0.0135"). Common for tap drilling and machine screw clearance holes.

Collection of vintage hand drills with wooden handles on a rustic workbench.

Photo by FFD Restorations / Pexels

Letter Drills (A–Z)

Range from A (0.2340") to Z (0.4130"), filling the gap between number and fractional sizes. Often used for precise tap drill sizing.

Detailed view of a hand operating a drill press in a workshop setting.

Photo by Sergei Starostin / Pexels

Fractional Drills (1/64"–1")

Standard imperial sizes in 64ths-of-an-inch increments — the most common bits found in home and shop drill sets.

Detailed black and white image of a Mitutoyo dial indicator measuring tool, showcasing precision engineering.

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Metric Drills (1mm–25mm)

Standard metric sizes in 0.5mm increments, used worldwide outside the US and increasingly common in modern shops.

Close-up of hands using hand tools on metal in a workshop setting.

Photo by Daniel Smyth / Pexels

Tip: Choosing a Tap Drill

Click any row to highlight it for quick reference while at the drill press. Use the search box to jump straight to a size (e.g. "1/4", "#7", "M5").