Canning Math

Deciding what to put up each summer is the easy part. Deciding how much is another matter entirely. Half the battle is in just knowing what your family is likely to eat for oh, say – the next year, until the next season for that item rolls around. But it’s not as difficult as you might think. Start with the list of things your family eats, that you have the ability to preserve yourself. For us, it’s the following –

–          Tomatoes

–          Applesauce

–          Apple pie filling

–          Apricot jam

–          Frozen blueberries

–          Frozen hot peppers

–          Frozen sweet peppers

Then think about an average month. At our house, we eat something with tomatoes almost once every other week. My son loves applesauce, so we definitely use a quart a month. We might eat an apple pie every six weeks. Frozen blueberries get sprinkled into pancakes or muffins every month or so. Apricot jam – I make a pork roast with it a few times a year, and use a little bit of it to glaze the tops of my apple pies sometimes. The peppers get used about once a week too. So the month looks like this –

–          Tomatoes – 2 quarts

–          Applesauce – 1 quart

–          Apple pie filling – 1 quart

–          Apricot jam – 1 pint

–          Frozen blueberries – 1 pint bag

–          Frozen hot peppers – 1 pint bag

–          Frozen sweet peppers – 1 pint bag

Then, simple math here – multiply your month by 12 to get your number for the year –

–          Tomatoes – 24 quarts

–          Applesauce – 12 quarts

–          Apple pie filling – 12 quarts

–          Apricot jam – 12 pints

–          Frozen blueberries – 12 pint bags

–          Frozen hot peppers – 12 pint bags

–          Frozen sweet peppers – 12 pint bags

But remember how I said I only do a pork roast with apricot glaze a few times a year? 12 jars is going to be way more than I need. So now we’re going to take that basic math list and adjust it slightly, depending on if we want a surplus of certain items, or even a little less of others (for things that we’re trying the first time and want to make sure we like, for example). We’re also going to adjust for canner batches. It doesn’t make sense to run a huge canner with only a few jars in it – I only like to run full canner loads. So since a standard canner holds 7 quarts, you want your total number divisible by 7. If you have a mini canner (that holds 2 quarts or 4 pints) that’s a great option for test recipes or small batches. So to adjust our list by need and canner load, it will look like this –

–          Tomatoes – 28 quarts, to account for 4 full canner loads and I’d rather have a surplus than deficit.

–          Applesauce – 14 quarts, to account for 2 full canner loads and I’d rather have a surplus.

–          Apple pie filling – 7 quarts for a single canner load. We eat closer to 7 pies a year than 12.

–          Apricot jam – 4 pints for a single mini canner load.

–          Frozen blueberries – 8 pint bags, because we eat a bit less than a pint a month.

–          Frozen hot peppers – 6 pint bags, because I won’t use an entire bag per use; typically only a quarter or half.

–          Frozen sweet peppers – 12 pint bags because that’s spot on what we use.

So there’s your canning tally. Now how much produce do you need? If you grow it yourself, this is where you’re starting to plan for next year’s (that’s right, next year’s) garden. If you buy it from a farmers market or farmer, you want to know how much cash you have to invest. Most basic canning recipes you’re going to calculate as weight by quart. So for example, most of the time apples will be 3 pounds per quart. Multiply the weight by the number of quarts you want, and you have the total amount of produce you need. To put up the amount of jars I want, I will need the following quantities of produce –

–      Tomatoes – 70 pounds (2.5 pounds per quart)

–      Applesauce – 42 pounds (3 pounds per quart)

–      Apple pie filling – 21 pounds (3 pounds per quart)

–      Apricot jam – 5 pounds (2.5 pounds per quart)

–      Frozen blueberries – 8 pounds (2 pounds per quart)

–      Frozen hot peppers – 6 pounds (1 pound per pint)

–      Frozen sweet peppers – 12 pounds (1 pound per pint)

Ball has a really handy produce purchase guide and seed-to-harvest guide on their website (which you can print to PDF if you’re so inclined), and the same information can also be found in the Blue Book and the Complete Book of Home Preserving.

If you’re a little OCD like I am, you can keep track of what you produce and use year over year in a spreadsheet. This is really helpful when you’re first starting out and learning what your family will not only use in a year’s time, but also what you’re willing to put up. You might not like to do everything. I personally tend to shy away from pickles, and I don’t do a whole lot of jams and jellies. Don’t get in over your head if you’re new to canning – there are a ton of great recipes to try, and it going to look very attractive on paper. But canning does take a little work, so it’s best to start small and have a great experience that you can build on next time, instead of having a monstrous canning project on your first time out that’s more work and more mess than you anticipated, making you never want to see another canning pot as long as you live. It’s okay to pick and choose what you decide to put up and what you don’t, and that’s half the fun of it anyway.

So, make your list – canning season is kicking into prime gear here so there’s still plenty of time this summer to get some goodies in the pantry.


3 thoughts on “Canning Math

  1. This is great information. I am a relatively new canner, and I do keep a spreadsheet to track what I have canned and what we use, and to also track my supplies – jars, lids, etc. That way, I don’t get caught without something at the last minute.

  2. Very smart to plan ahead. Also good advice to keep track of what’s in your cupboard and freezer so it doesn’t get lost, and you know how much to put away next year.

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