The Blender Unit is the default unit of measure in Blender. They are similar to millimeters, centimeters, meters, etc. Except Blender Units don’t actually correlate to anything in the real world.
I typically like to model using centimeters and meters. You know, the metric system. Sometimes I use inches and feet. I almost never use Blender Units. But that’s just my preference.
Although Blender definitely supports both metric and Imperial units in addition the default, I had a heck of a time finding where to change the setting. I looked through user preferences at least two times.
Turns out it was hiding in the scene tab. Actually, that’s a very reasonable place for measurement settings to be. User settings would be a foolish place to have this. Foolish! Interestingly, the so called Blender Units are listed here as, “None.” Metric and Imperial are listed as would be expected. Do Blender Units really exist?
For anyone familiar with Inkscape, I think the scene tab can be thought of as Blender’s version of document settings.
Fun completely unrelated fact: Blender retains measurements when importing SVG files. So, for example, if you were to model some 2D objects in Inkscape using the metric system, those sizes would be preserved when importing into Blender.
Stay tuned for more Blender (and Inkscape) how-to goodness.