Understanding Vinyl Pool Liner Thickness


When talking about the “mil” or “guage” of vinyl pool liners, you should first get a decent understanding of what these terms actually mean. The most common term for vinyl, “mil” (not to be confused with millimeter) is a unit of measurement equal to one thousandth of an inch. Therefore, a 20 mil liner thickness is equal to 20 thousandths of an inch. The term “gauge” (not to be confused with mil), is a bit more of a moving target. See, multiple industries measure items such as wire, shotgun barrels, sheet metal, photographic film and hypodermic needles by their gauge. This can be very confusing as in a case like shotgun barrels where the smaller the gauge, the larger the barrel. This is not the case when it comes to vinyl pool liners where the higher the gauge, the thicker the material.

When shopping for pool liners, it is very important that you are aware that gauge is not equal to mil. Some manufactures or retailers like to offer their liners in terms of gauges because they sound thicker than a true mil. To be technical, a 30 mil liner is equivalent to 0.0300 inches. A 30 gauge liner is equivalent to 0.0260 inches (26 mil). Therefore, if you see a liner advertised at 35 gauge, it is truly a 30 mil liner. To avoid this confusion, always make sure and purchase from a company that advertises in mil, versus gauge.

To give some additional perspective, here is the mil of some everyday items:

Item Thickness (in mils)
Standard sheet of paper 10 mil
Dime 49 mil
Human hair 2 mil

When deciding what’s best between the thicknesses of vinyl pool liners for in ground pools, a variety of factors should be considered. Such as the location of the pool in relation to sun exposure, how much time the pool will spend covered and the type of surface the liner will be laid on.

If the pool will experience longer exposure to direct sunlight throughout the year or when you’re dealing with a rougher surface material, such as a concrete or a sand and concrete mixture, the appropriate, preferred mil of vinyl pool liner would be the 28-30 mil. Although thicker material will typically cost you about 5 – 10% more, it is 29 – 32% thicker than 20 mil, and will no doubt provide adequate thickness and protection for its purpose.

With that being said, all pool liner material, no matter the thickness will boast the smooth nature vinyl is famous for, come in an array of patterns to choose from, and in most cases, carry the same warranty.

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  1. Elainemgonzalez on June 10, 2012 at 2:29 pm

    Very informative info. Thanks.

  2. Vic on May 3, 2013 at 3:59 pm

    Thanks a lot for the explanation, please suggest me what vynil patches should I use to cover a 10 inches vertical seam cut in my swiming pool of 12X48 above ground with metal bars frame branded Intex.

    • Bob Cannon on May 6, 2013 at 8:01 am


      Patching a seam is difficult enough but 10” makes it even
      more of a challenge. Your best bet would be to obtain material from the
      manufacture of your liner (if possible) and good vinyl adhesive. Using the same
      material your pool is made of will make it easier to work with and ensure a
      better bond.

      Best of luck!


  3. Minerva Garza Wilson on June 19, 2013 at 6:39 am

    So which gauge is better 20g or 25g

    • Ann on June 19, 2013 at 3:04 pm

      I am taking a pool from a friend. He has had it three years no longer wants it due to health reasons. it is above ground 24. I guess i should replace the liner. What type of gauge should i get and should i use a pad between the liner and pool frame?

      • Bob Cannon on July 24, 2013 at 6:53 am


        When moving an above ground (steel wall) pool from one location to another, it will definitely be required that you replace the liner. I would request from your local dealer, the thickest liner they have available for that style of pool. The range for above ground pools is usually anywhere from 12 mil – 20 mil and sometimes can be found as thick as 27 mil. The benefits of having a thicker liner will most always outweigh the minimal cost difference in upgrading from the thinner to the thicker mil. Lastly, there should always be some type of protective layer beneath the liner. On our pools, if it is going on top of concrete, we place a foam pad down under the liner. If the pool is going on dirt, we use a non abrasive material called Provisil or a light silica sand. Best of luck with your new pool.


    • Bob Cannon on July 24, 2013 at 6:55 am


      With vinyl, a good rule of thumb is: The higher the number, the thicker the material.
      I hope this helps.


      • Guest on April 15, 2014 at 1:06 pm

        higher is better only if the measurement your referring to is mil…the higher the gauge measurement the thinner it will be.

        • PoolMan on June 6, 2014 at 8:33 am

          This is SSSOOOO not true. Just the opposite.

        • Barney on June 4, 2016 at 5:32 pm

          No, the information above states that the higher the ga, the higher thicker the vinyl.

        • publicinterestjournalist on February 10, 2018 at 4:53 pm

          “Guest” is wrong. In “gauge” size goes up as number goes down only when discussing SHOTGUN BARRELS–not vinyl fabric!!!!!!!!!! With vinyl, gauge is a little smaller than a similar size in mils.

        • Ted Williams on October 30, 2019 at 8:54 am


  4. Ivy on July 4, 2013 at 12:08 pm

    Thanks for this post, it really helps!

  5. Michael Kern on January 25, 2014 at 8:01 am

    This is a great article, so many companies prey on the ignorance of the typical customers. I live and work in Massachusetts where winters can be quite harsh, and we have professionals recommending overlap liners that are 15 gauge just to make a sale.
    BTW…Typo Second Paragraph…Ticker=thicker

    • Bob Cannon on January 30, 2014 at 6:34 am

      Glad you enjoyed the info Michael. It’s hard finding a reputable company sometimes. Even harder finding a reputable editor…. Thanks for the heads up on the typo.


    • Guest on April 15, 2014 at 1:12 pm

      15 gauge would be a very thick liner…here again, the smaller the gauge number the thicker the liner. However when measuring in millage (mil) the higher the number the thicker the liner. the measurements work in reverse of each other.

      • PoolMan on June 6, 2014 at 8:35 am

        Not true! Are you nuts? it’s not like needles!! The pool factory 25 gauge is thicker than the 20 gauge!!! Any company that does it opposite is crazy.

      • publicinterestjournalist on February 10, 2018 at 4:48 pm

        Kern is wrong. “Gauge” goes up as number goes down when discussing SHOTGUN BARRELS–Not vinyly fabric!!!!!!!!!!

      • publicinterestjournalist on February 10, 2018 at 4:49 pm

        Kern is wrong. “Gauge” goes up as number goes down when discussing SHOTGUN BARRELS–not vinyl fabric!!!!!!!!!!

  6. guest9823456 on May 27, 2014 at 4:20 pm

    Higher gauge means thinner if buying from The Pool Factory

  7. guest9823456 on May 27, 2014 at 4:21 pm

    Oops typo higher gauge means THICKER at The Pool Factory

    • PoolMan on June 6, 2014 at 8:34 am


  8. jayjay on April 5, 2015 at 7:02 pm

    Which is better 20 gauge or 25 which is thicker

    • Bob Cannon on April 7, 2015 at 12:55 pm

      Typically with vinyl, the higher the number, the thicker the material.

  9. Tony Tudor on May 2, 2017 at 7:28 am

    can you use a jhook liner on a doughboy pool that you have been using the one that folds over the top>

    • Bob Cannon on May 2, 2017 at 2:12 pm

      That’s a good question Tony. It depends on the track that is going over the liner. My advise would be to stick with what you have used in the past or you may need to change additional parts / pieces.

  10. deerJoan Runnels :) on August 19, 2017 at 7:04 pm

    what is 80 gauge in mill

  11. deerJoan Runnels :) on August 19, 2017 at 7:05 pm

    what is better 80 gauge or 12mil

  12. Buzzy Williamson on October 30, 2019 at 8:55 am