What is the difference between Mil and Gauge?

In vinyl pool liners

Do you want to know what the difference between Mil and Gauge in vinyl liners? Well we will explain it for you. They are both measurements of thickness. A liner that is advertised as a 20 mil usually has a 20 mil bottom and a 15 mil sidewall. A 20 gauge liner means that the liner has a 20 mil bottom and a 20 mil sidewall. So a 20 Gauge liner is going to be a little thicker.

Please check out this chart for further explanation

Liner Sidewall and Bottom Thickness=Liner Category
15 Mil side / 20 Mil bottom =	20 Mil Liner
20 Mil side / 20 Mil bottom =	20 Gauge Liner
20 Mil side / 25 Mil bottom =	25 Mil Liner
25 Mil side / 25 Mil bottom =	25 Gauge Liner