Vinyl Liner Thickness: Gauge versus MIL

The purpose of this article is to clear up the common confusion when comparing MIL thickness to gauge when discussing vinyl liner material.

It is important to note first and foremost that “GAUGE” has no meaning in the plastics field. Gauge is a unit of measurement without a specific distance; this is dependent on what you are measuring. For example, a 12 gauge shotgun barrel is different than a 12 gauge wire but in both cases the higher number is a smaller unit.

Sheet metal is commonly specified by a traditional, non linear measure known as it’s “gauge”. The larger the gauge number, the thinner the metal. The same is true for electrical wire gauge, the larger the gauge measurement the smaller the size of the wire.

The definition of MIL is the UNIT OF LENGTH EQUAL TO 1/1000 INCH USED ESPECIALLY IN MEASURING THICKNESS (AS PLASTIC FILMS). MIL is a North 

American measurement (imperial measurement) that is equal to 1/1000^th of an inch in thickness.

MIL measurements have nothing to do with the metric measurement millimeter. Due to the way that these measurements are acquired, 27 MIL vinyl is thicker than 20 MIL vinyl but 20 gauge or 20G Vinyl is a meaningless term without measure.

While the term gauge is not a “real” term it is unavoidable within the pool industry due to internet marketing and the need for pool liner manufacturers to follow suit to market their product.

At 21^st Century Pools & Spas our stock aboveground liners are 17 MIL standard and hold a 20 or 25 year warranty depending on the brand of liner that is chosen. It is important to ask all retailers, online or otherwise, what their liner MIL thickness is as that is the only real measurement for vinyl liners. It is also useful to ask for warranty information to ensure your investment is adequately covered.