Gauge in MM

Every time, when it comes to gauge in mm, I get a little bit confused.

Since I am used to the measure of mm (millimeter), I cannot easily exchange mm into gauge number in my mind.

And I believe that some people like gauge number better than mm on the other hand.

The numbers of the table below is from internet.

For quick reference, I made a simple table of gauge in mm (millimeter). 

Gauge in mm table