Looking for a quick way to tell the thickness of a line, part of a outline or a ring.

[A.K. Hershey]

The only way I can find it to turn on smart guides and use the line tool to create a line from one end to the other.  Like below

[Myra Ferguson · Accepted solution]

The Astute Graphics plugins (which are available as a separate subscription) include Dynamic Measure:

• https://astutegraphics.com/learn/10minskills/measure-easier-in-illustrator

[Mike_Gondek]

Click on the 3 dots to edit tools

Scroll down

Drag and drop the measure tool to add to tool

escape to exit