Drill Gauge Bit Index: How to Identify Drill Bit Sizes
By Drill Hog® | Published: 2026-10-27
Category: How-to Guides
Learn how to quickly identify drill bit sizes using a drill gauge. This guide covers wire gauge, fractional, and diameter measurements from 1/16 to 3/4 inch.
Quick answer
To identify any drill bit size from 1/16 to 3/4 inch, use a drill gauge bit index like the Drill Hog 29 Size Drill Gauge. Insert the bit into the matching hole; the labeled hole tells you the exact fractional or wire gauge size.
Why a drill gauge is faster than measuring
A drill gauge eliminates guesswork. Instead of using calipers or rulers to measure diameter, you simply drop the bit into the closest hole. The gauge is marked with fractional sizes (e.g., 1/16", 3/32", 1/4") and wire gauge numbers, so you get an instant reading.
The main trade-off is that a gauge only works for bits within its range. The Drill Hog gauge covers 1/16" to 3/4", which handles most common twist drill bits. If you work with larger or metric bits, you would need a separate gauge.
Understanding wire gauge vs fractional sizes
Drill bits come in two common labeling systems: fractional inches (like 1/4") and wire gauge numbers (like #7). A wire gauge number does not directly match a fractional inch—for example, a #7 bit is 0.201" diameter, while a 13/64" bit is 0.203". A drill gauge with both markings lets you identify either system.
The Drill Hog gauge includes 32 holes labeled with fractional sizes, making it easy to match any standard fractional bit. If you have a bit with only a wire gauge number, you can still find its matching hole by trial fitting.
How to identify drill bit sizes with a gauge
- Clean the bit shank: Wipe off any oil, dirt, or debris from the drill bit. A clean surface ensures the bit fits snugly into the correct hole without false readings. A dirty bit may slide into a slightly larger hole and give you the wrong size.
- Insert the bit into the gauge: Hold the drill gauge flat and try the bit in the smallest hole it seems to fit. Push it straight in—do not force it. The correct hole will accept the bit with a light friction fit. If the bit wobbles or passes through too easily, try the next smaller hole.
- Read the labeled size: Look at the marking next to the hole that fits. The gauge shows the fractional inch size (e.g., 1/4") and sometimes the wire gauge number. That is the drill bit size. If the bit fits between two holes, it may be a metric or non-standard size. Use a caliper for those.
- Check for wear or damage: A worn or chipped bit may measure undersized. If the bit fits a hole smaller than its marked size, the cutting edge is likely worn. Replace or sharpen it. A damaged bit can cause inaccurate holes and should not be used for precision work.
Product facts
- Drill Hog® Drill Gauge Bit Index Bolt Wire Diameter 1/16" to 3/4": The Drill Hog 29 Size Drill Gauge has 32 holes from 1/16" to 3/4", covering fractional sizes including 1/16", 5/64", 3/32", and so on up to 3/4". This wide range means you can identify nearly any standard fractional drill bit in your workshop without needing a separate tool.
Drill Hog® Drill Gauge Bit Index Bolt Wire Diameter 1/16" to 3/4"
