How to Convert a Metric Drill Bit to Standard

Updated February 21, 2017

Mankind has used drills for thousands of years to create perfectly round holes in wood and steel. The first known mechanical drill was invented by the Egyptians and used a bow to turn the bit. The drill bits job is to auger the hole and remove the material. Drill bits come in a variety of sizes to assist with any job and maybe sized using the metric or imperial system. This information is engraved into the side of the bit.

Hold the drill bit by its cutting end and rotate the bit until you see the engraving in its smooth end.

Record the size measurements or designation number off the bit. The size looks something like ".508 mm" or "3/8" and the designation number appears like "#45."

Click the link found in the resource section to the drill bit size chart. Locate the size of the bit using the columns, then look across to find the corresponding size in metric or imperial. Common sizes are: 1.5875mm = 1/16 inch, 3.175mm = 1/8 inch and 4.7625mm = 3/16 inch.


Always wear safety glasses when operating a drill. This keeps foreign objects from damaging your vision.

Cite this Article A tool to create a citation to reference this article Cite this Article

About the Author

Bob White began his writing career in 2006. Working in sales, he was a technical writer tasked with responding to requests for proposal. White has a Bachelor of Arts in computer science and a diploma in home inspection. He has also worked in construction, landscaping and the pool industry for more than 15 years.