Home Canning Success Tips: The Importance of Proper Headspace

There are methods used in home canning that might seem like insignificant details to the beginner and you might wonder why do I need to worry about that?  One of those things is the recommended proper headspace in the jars, or in other words how full to fill them with the food or added liquid.

Head space is the empty space between the top of the jar and the top of the food or liquid in the jar and it is important to insure a proper vacuum seal of the jar lids which is the difference between food that is safe to eat and food that will make you bad sick.

If too little headspace is allowed the food may expand and bubble out of the jar during the processing when air is being forced out of the jar. This can soil the rubber coating on the jar flat lids causing them not to make a tight vacuum seal.

When too much headspace is allowed there can be discoloring of the food in the top of the jar and also the jar may not seal properly because not enough air is forced out during the the processing.

Most canning recipes tell you the proper headspace to use for that specific food but general headspace guidelines are as follows:

• 1/4 inch headspace for jams and jellies
• 1/2 inch headspace for fruits and tomatoes processed in boiling water bath 
• 1 inch to 1-1/4 inch headspace for low acid foods (meats and vegetables) processed in a pressure canner

It is best to have a headspace measuring tool but you can also use certain points on the jar and rings to measure it. The more you can food, the better you get at this.

• From the top shoulder of jar to the lid is 1"
• The protruding shelf like part of the jar that the rings sit on when tightened is the lip. From the lip of the jar to the lid is  1/2" 
• From the first crimp in the metal ring to the lid is 1/4 " 

When you get the headspace correct you are more likely to have good success with your jars sealing and confidence in the food being safe for your loved ones or customers to eat. If a lid of a jar doesn't require a can opener to pry it off and make a discernible sound of the vacuum unsealing, do not use it. This is an indication that the jar was not properly sealed.  There is also a special "ting" sound the lid makes when you tap it with a spoon or fingernail.  If it goes "thud" or "thunk" instead of "ting" it is not vacuum sealed.  Practice learning what that sounds like with your well sealed jars because this is something you have to hear to be able to recognize the right the sound...  just don't tap too hard and damage the seal.


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It comes in two sizes and it is easy to write in the details with a sharpie marker!

Buy it HERE