Understanding Mason Jar Lid Sizes

written by Phillip Jacobsen on August 26, 2013 in articles with no comments

Understanding Mason Jar lid sizes can be a bit confusing at first.  Here is a quick guide to buying the correct sized lids for your jars.  The size of the lid is not dependent on the volume of the jar so you need to make sure you check the opening size.

There are 3 different opening sizes that you may encounter on your jars.

  • “Regular” or “Standard” opening (70mm)
  • Gem or Improved Gem opening (78mm) (jars are no longer being manufactured)
  • “Widemouth” opening (86mm)

Mason Jar Lid Sizes

Regular and Widemouth Jars are the only jar sizes that can be purchased now however in the past there was a third sized jar referred to as a Gem or Improved Gem jar made in Canada by Bernardin.  As far as I know this size of jar was not made by any American company.  The Gem jar became the most common sized mason jar used in the prairies of Western Canada.  This is the size of jar that my mother used when I was growing up and I have hundreds of these jars that I have inherited from various people.  In 1993 Bernardin was purchased by Jardin in the USA who also manufactures the Ball and Kerr brands of mason jars.  A new manufacturing plant was built and they discontinued the manufacturing of Gem size jars and lids.  The inability to no longer buy the Gem jars was not nearly as much of a problem as the possibility of not buying the disposable lids for the hundreds of thousands or even millions of the Gem jars that were still being actively used.  A group of Canadians that consisted of home canners, 27,000 members of the western Hutterite communities, and  the minister of agriculture petitioned Jardin to continue the production of the lids.  As a result of this petition Jardin put the gem lids back in production in 2003.

Here are a couple of links to the interesting story.


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    I am the co-founder of Greenmunch. I was raised on a farm in southern Alberta, Canada. After graduating from Electrical Engineering I worked in the consumer electronics industry designing lots of cool widgets. After 11 years I decided I wanted to pursue some of my other interests. In 2011 I launched Greenmunch along with my wife Joy.

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