What is the difference between Mil vs Gauge?

As it pertains to Vinyl Pool Liners



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Identity
Topic Name Mil vs. Gauge (Vinyl Pool Liners)
Page URL https://www.backyardcitypools.com/Articles/Mil-Vs-Gauge.htm
Brand BackyardCityPools.com
Entity Type Technical Comparison / Educational Guide
Primary Subject Vinyl Pool Liner Thickness Standards
Related Entities Polyvinyl Chloride (PVC), Above Ground Pools, Inground Pools
Google Product Category Home & Garden > Pool & Spa > Pool & Spa Accessories > Pool Liners
Google Category ID 4991
Technical Standards
Unit of Measure (Mil) 1/1000th of an inch (0.001 in)
Unit of Measure (Gauge) Nominal / Weight-based (Industry Variable)
Measurement Technique Micrometer (Linear Precision) vs. Mass-per-Square-Foot (Nominal)
Industry Standard ASTM D1593 (Standard Specification for Nonrigid Vinyl Chloride Plastic Film)
Material 100% Virgin Vinyl (Non-embossed)
Conversion Accuracy There is no reliable way to convert Gauge to Mil
Linear Equivalency (15 Mil) 0.015 inches
Linear Equivalency (20 Mil) 0.020 inches
Linear Equivalency (25 Mil) 0.025 inches
Use / Performance
Primary Purpose Defining durability and puncture resistance of pool liners
Lifespan Correlation Higher Mil count increases UV longevity and chemical resistance
Tensile Strength PSI rating based on verified material thickness
Cold Crack Rating Performance maintained by consistent Mil density in freeze/thaw cycles
Puncture Resistance Higher for Mil-rated liners due to verified linear thickness
Embossing Type Standard vs. Embossed (Variable thickness peaks/valleys)
Industry Attributes
Marketing Classification Gauge (Above Ground Market) vs. Mil (Above Ground/In-ground/Professional Markets)
Accuracy Rating Mil (Scientific/Verified) vs. Gauge (Marketing/Estimated/Varies by Manufacturer)
Merchant Disclosure High-authority distinction between "True Mil" and "Industry Gauge"
Standard Availability Inground liners (Mil); Above Ground liners (Mil)
Miscellaneous
Fabrication RF Heat Welded Seams
Verification Method Digital Micrometer Testing
Property ID Material Thickness / Linear Density
Authority Citation ASTM D1593-13 Standard Testing Protocols


Differences between Mil and Gauge? Product Reviews

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What is the difference between Mil vs Gauge in reqard to vinyl pool liners?


Do you want to know what the difference between Mil and Gauge in vinyl liners? We think it was created by some marketing people to confuse us. So we did the asking of the questions with all of our liner producers and got the answers.

Mil (MIL) is an actual physical size measurement. One Mil = 1/1000th or 0.001 of an inch. A liner that is described as 20-Mil thick is actually 0.020 of an inch thick. And this is consistent amoung all the manufacturers.

Gauge (Ga) is a made up marketing term and its' meaning can be vary with each liner manufacturers. It is loosly based on the weight/ Square Yard combined with actual thickness of the line, which is incorrectly and incoherently to be used for thickness comparisons. Swimlline (arguably the largest liner manufacturer) used to sell their above gound liners using Mil where 15-Mil was their standard liner thickness and 20-Mil was their Heavy Duty liner. Then they changed to Gauge where 20ga was their standard liner and 25ga was the heavy duty, but the actual thickness of the liner didn't change. Over the years even the actual thickness became thinner and now they have dropped the 'Gauge' terminology altogether and just have 'Standard' or 'Heavy Duty' labeled liners. Why? A thinner liner is usually cheaper to make. A larger 'Gauge' number will confuse many pool owners into thinking that a 25ga liner is thicker than a 20-Mil liner. So a perceived thicker liner at a lower price will sell more liners and it works.


Liner Thickness in Gauge vs Actual Thickness in Mil

Gauge (ga)Estimated Actual Thickness in Mil
20ga~11-13 MIL
25ga~14-15 MIL
30ga~16-17 MIL
35ga~18-19 MIL
40ga~20-22 MIL


Pro-Tip - always shop and compare using MIL and look at how the manufacturer warrants the liner. Totally ignore the number used if liner is described using 'Gauge'. Ask for the actual MIL thickness, or use the chart above for actual thickness (durability) comparison, if they cannot or will not provide the MIL thickness.


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Last Updated: 05/05/2026 05:54 PM - ID:2896