Canning 101...Who Cares About Headspace?

     The space in the canning jar from the underside of the lid to the top of the food or liquid in the jar is called the headspace.  Too little headspace, and the food may bubble over during processing.  The residual food may interfere with the seal of the lid, not to mention making a mess in the canner.  Too much headspace and the food at the top may discolor in storage.

     Too little headspace is usually my problem if I'm going to have one.  There's nothing worse than canned salmon over flowing it's jar in the pressure canner!  Learning where the headspace is on your jar really helps a lot.

Turn your jar to where the threads "overlap".
That is not necessarily the front of the jar.

1/4 inch is at the first thread.
1/2 inch is at the middle thread.
1 inch is just below the "finish". (just below that last "thread")
1 1/4 inches is halfway down the shoulder.
1 1/2 inches is just below the shoulder.

     When you are using your jar filler, get used to where these marks are on your filler.  On my filler, just to the bottom of it is 1 inch.  The more you can, knowing where your headspace marks are, just comes naturally.

     Different foods have different headspace because of how that food expands or doesn't expand in the jar.  Your recipe usually tells you how much headspace you should leave.  When I can foods to compete at my county fair, headspace is very important to the judge.  The wrong headspace will be disqualified right away.  These are the headspaces required for our fair, and in general, what you should use for everyday canning.

Jams and Jellies.......1/4 inch
Pickles......................1/2 inch
Fruits........................1/2 inch
Tomatoes.................1/2 inch
Vegetables...............1 inch
Meats.......................1 to 1 1/2 inches

Read the rest of the series (just getting started):
Canning 101 -- Why 2-Piece Lids?


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Intentional Living Homestead said...

Wow, I knew the word "headspace" but had no idea how far down it meant...thank you for the chart.


Rae said...

That is some really useful information. I've only canned a few times, but this is some helpful info to hang on to for my next venture. Thanks.

Candy C. said...

I knew it had something to do with the threads but wasn't exactly sure. You explained it perfectly! Thanks!

Unknown said...

Wow! I love that quick tutorial! Thanks! And also a thank you for the surprise post of my blog in your sidebar. I hesitated to do that piece, so I tried to find a way to keep it light. When I travel to Cincinnati, the homelessness there is just awful and I'm sure some people end up in that situation by surprise, slipping through the cracks, and not because they are throw-away people.

jesblu00 said...

THe easiest to understand tutorial on headspace! Thanks.

Kim@stuffcould.... said...

They do need a dad does this

Stephanie said...

Thank you!!!!

Gorges Smythe said...

Thanks for the info. I'll save that!

Unknown said...

Great reference tool!

3rnigerians said...

Dr. Momi,
Thank you for clearing this up. I have been a bit confused about this. I have different late model canning books that give differing headspace rqs. I remember that you're a master canner, something I'd love to be someday if the program gets up the mountain, but for now this helps immensely. Thanks so much.

Julie said...

Great post. I never realized the notches of the rings could help with the headspace. I just always "guesstimate" at 1/4 in when doing my jelly & jams!

Thank you for this useful info!

Anonymous said...

Great info! I use this myself. I've never done meats before, though this year I plan to try some. Thank you for the chart; it is most helpful.

Carol Urban said...

I always had problems when I canned vegetables so I ended up giving it up. Now I may try again. Thank you!

dr momi said...

Hey Carol....I hope you do start canning those veggies again! We love our green beans canned....thanks for the follow!

Unknown said...

This is a great site with lots of very helpful tips and lessons. I'm so glad I came across it!