Canning Jar Calculator
Jars Needed
—
Buy This Many (with extras)
—
Total Volume
—
Headspace Per Jar
—
Planning Your Canning Project
Knowing how many jars to prepare before you start canning saves time and prevents waste. This calculator converts your recipe yield in cups to the number of jars needed, accounting for headspace — the empty space between the food and the lid that is essential for proper sealing.
Headspace requirements vary by recipe type: jams and jellies need 1/4 inch, most fruits and pickles need 1/2 inch, and low-acid foods processed in a pressure canner typically need 1 inch. Proper headspace allows food to expand during processing and creates the vacuum seal that preserves food safely.
Always buy 10-15% more jars than you think you need. Jars can crack during processing, yields may vary from estimates, and having extras on hand prevents mid-session trips to the store. New lids are required for each canning session, but glass jars and bands can be reused indefinitely if undamaged.
Frequently Asked Questions
How many jars do I need for a bushel of tomatoes?
A bushel of tomatoes (about 53 pounds) yields approximately 15-20 quart jars of whole or halved tomatoes, or 12-16 quarts of tomato sauce, depending on the variety and cooking method.
Can I reuse canning jars and lids?
Glass jars and screw bands can be reused if undamaged. However, flat lids with the sealing compound must be new for each use to ensure a proper vacuum seal. Never reuse lids.
What is the correct headspace for canning?
It depends on the product: 1/4 inch for jams and jellies, 1/2 inch for fruits and pickles, and 1 inch for most vegetables and meats. Always follow your tested recipe headspace recommendations.
What size jars should I use for canning?
Half-pint (8 oz) jars are ideal for jams, jellies, and salsas. Pint (16 oz) jars work well for pickles, relishes, and sauces. Quart (32 oz) jars are best for whole fruits, tomatoes, and large-batch items.