Whether you’re working on a DIY project or trying to figure out the size of something you’re buying online, you’ve probably needed to convert millimeters (mm) to inches (in) at some point.
The metric system is used worldwide, but in the United States, we still use the imperial system for many measurements. That makes converting between millimeters and inches a common, everyday need.
This article is a guide to understanding and converting mm to inches, with a focus on converting 39mm in inches. We’ll cover the definitions of each unit, the conversion formula, and some real-world examples.