Canning & Preserving Calculator
Estimate how many jars you need to preserve your garden harvest. Covers water bath canning, pressure canning, and freezing.
A 20-pound harvest of tomatoes fills roughly 7 quart jars using water bath canning, taking about 2 hours across a single batch. This calculator helps you plan jars, batches, processing time, and shelf life for 10 common garden crops so nothing goes to waste.
Data last updated: March 2026
Tomatoes: 3 lbs per quart, 1.5 lbs per pint
Canner holds 7 quarts per batch
Your Canning Plan
Breakdown
Recommended Canning Supplies
Ball Mason Jars
Pint and quart canning jars with lids and bands. The gold standard for home canning.
Pressure Canners
Essential for low-acid foods like green beans, corn, and beets. Safe and reliable models.
Canning Starter Kits
Jar lifter, funnel, bubble remover, lid wand, and tongs. Everything you need to get started.
Frequently Asked Questions
Water bath canning uses boiling water (212 F) to process jars and is safe for high-acid foods like tomatoes, pickles, jams, and fruit. Pressure canning uses pressurized steam to reach 240 F, which is required to safely preserve low-acid foods like green beans, corn, beets, and peppers. Using the wrong method for the food type can lead to dangerous bacterial growth, including botulism. Always follow USDA or Ball guidelines for which method to use.
How This Calculator Works
This calculator estimates the number of jars needed by dividing your harvest weight by the average pounds-per-jar yield for each produce type. Yield rates are based on USDA and Ball canning guide recommendations. Batch counts assume a standard water bath or pressure canner that holds 7 quart jars or 9 pint jars. Total time includes both processing time and approximately 30 minutes of prep per batch for heating the canner, loading jars, and cooling.
Tips for Successful Canning
- Always use tested recipes from the USDA, Ball, or your local cooperative extension. Do not modify acid levels, processing times, or jar sizes from tested recipes.
- Low-acid foods (green beans, corn, beets, peppers) require pressure canning for safe preservation. Water bath canning is only safe for high-acid foods like tomatoes, pickles, jams, and fruit.
- Check jar seals after cooling. Press the center of the lid. If it does not flex up and down, the seal is good. Unsealed jars should be refrigerated and used within a week.
- Label every jar with the contents and date. Use the oldest jars first. Most home-canned goods maintain best quality for 12 to 18 months when stored in a cool, dark place.
Never Miss Planting Season
Get seasonal reminders straight to your inbox — we'll tell you when to start seeds, transplant, and harvest.
Affiliate disclosure: We may earn a commission from links on this page. Learn more.