Canning Yield Calculator
Calculate how many jars you will get from a given amount of fresh produce for canning. Enter values for instant results with step-by-step formulas.
Reviewed by Daniel Agrici, Founder & Lead Developer
Formula
Total Jars = (Fresh Pounds x (1 - Prep Loss)) / Pounds Per Jar
Where Fresh Pounds is the starting weight of raw produce, Prep Loss accounts for peeling, coring, husking, and trimming waste as a percentage, and Pounds Per Jar is the amount of prepared produce needed to fill one jar of the selected size.
Worked Examples
Example 1: Canning 20 Pounds of Tomatoes
Problem:You have 20 lbs of fresh tomatoes and want to can them in quart jars. How many jars will you get?
Solution:Prep loss for tomatoes: 10% (coring, peeling)\nUsable weight: 20 x 0.90 = 18 lbs\nLbs per quart: 3.0 lbs\nTotal jars: 18 / 3.0 = 6 quart jars\nLeftover: 0 lbs\nProcessing: Water bath, 45 min per batch\nSupply cost: 6 jars x $1.25 + 6 lids x $0.30 = $9.30
Result:6 quart jars | Water bath processing | $9.30 in supplies | ~2 hours total time
Example 2: Corn Canning from Fresh Ears
Problem:You have 25 lbs of corn on the cob. How many pint jars of corn kernels can you produce?
Solution:Prep loss for corn: 55% (cobs, husks, silk)\nUsable weight: 25 x 0.45 = 11.25 lbs kernels\nLbs per pint: 4.5 x 0.5 = 2.25 lbs\nTotal jars: 11.25 / 2.25 = 5 pint jars\nProcessing: Pressure canner required (low acid), 85 min per batch\nSupply cost: 5 x $1.00 + 5 x $0.30 = $6.50
Result:5 pint jars | Pressure canner required | $6.50 in supplies | ~3 hours total
Frequently Asked Questions
How many pounds of produce do I need per jar when canning?
The amount of fresh produce needed per jar varies significantly by food type and jar size. For quart jars, general guidelines are roughly 3 pounds of tomatoes, 2.5 pounds of peaches or pears, 2 pounds of green beans, and 4.5 pounds of corn on the cob to yield kernels. These numbers account for the usable portion after preparation losses like peeling, coring, and trimming. Pint jars require approximately half these amounts, while half-pint jars need about one quarter. Always purchase 10 to 15 percent more produce than the calculated minimum to account for varying sizes, bruised spots, and under-ripe pieces that may need to be discarded during preparation.
What is the difference between water bath and pressure canning?
Water bath canning and pressure canning are two fundamentally different preservation methods suited for different food types based on their acidity levels. Water bath canning heats jars to 212 degrees Fahrenheit, the boiling point of water, which is sufficient to destroy molds, yeasts, and some bacteria in high-acid foods with a pH below 4.6. This method works for fruits, jams, jellies, pickles, and tomatoes with added acid. Pressure canning reaches temperatures of 240 to 250 degrees Fahrenheit under pressure, which is necessary to destroy Clostridium botulinum spores in low-acid foods like vegetables, meats, and soups. Using the wrong method for a food type can result in dangerous botulism contamination.
Can I reuse canning jars and lids from year to year?
Standard Mason-type canning jars can be reused many times as long as they remain free of chips, cracks, or scratches on the rim that could prevent a proper seal. Always inspect jar rims carefully before each use by running your finger along the edge to feel for nicks. However, standard flat metal canning lids with the sealing compound should only be used once because the sealing compound deforms during the first use and cannot create a reliable vacuum seal a second time. Metal screw bands can be reused if they are not rusted or bent. Some newer reusable lid systems like Tattler lids are designed for multiple uses, though they require slightly different techniques for proper sealing.
What common mistakes should beginners avoid when canning?
The most critical mistake beginners make is using untested recipes or modifying tested recipes, which can alter acidity levels and create conditions favorable to botulism growth. Always use recipes from trusted sources like the USDA Complete Guide to Home Canning or the Ball Blue Book. Other common errors include failing to properly sterilize equipment, not removing air bubbles from packed jars before sealing, over-tightening or under-tightening screw bands, and processing for insufficient time. Altitude adjustments are frequently overlooked as well, since water boils at lower temperatures at higher elevations, requiring longer processing times or higher pressure settings. Starting with high-acid foods like jams and pickles is recommended before attempting low-acid pressure canning.
References
Reviewed by Daniel Agrici, Founder & Lead Developer · Editorial policy