Pressure Canning Calculator

For low-acid foods at 5,000 feet, this calculator gives 12.5 psi on a dial-gauge canner (10 psi base plus 0.5 psi per 1,000 feet). The USDA banded table reads 13 psi for 4,001-6,000 feet - always round your setting up to the next band value, never down. On a weighted-gauge canner, use the 15-pound weight (the smallest weight at or above 12.5 psi).

No. Green beans are a low-acid food (pH above 4.6), and Clostridium botulinum spores survive boiling water at 212F (100C). Only a pressure canner reaches the 240F+ needed to destroy them. Water-bath canning low-acid foods risks botulism, which can be fatal. Pressure-can green beans 20 minutes for pints or 25 minutes for quarts.

No. Altitude changes the required pressure, not the time. A quart of raw-pack green beans processes 25 minutes at sea level and 25 minutes at 5,000 feet - but the gauge must read 12.5 psi (dial) or use the 15-pound weight (weighted) at 5,000 feet instead of 10 psi.

Both are safe when used correctly. A dial gauge shows exact pressure and needs yearly accuracy testing (your local extension office usually tests them free). A weighted gauge rocks or jiggles at 5, 10, or 15 psi, never needs calibration, but only offers those three settings - above 1,000 feet you must use the 15-pound weight. Weighted gauges are simpler; dial gauges are more precise.

Leave 1 inch of headspace for vegetables, soups, stocks, and tomatoes, and 1 to 1-1/4 inches for meats. Correct headspace lets air vent during processing so a strong vacuum seal forms as jars cool.

Venting - letting a full funnel of steam escape for 10 minutes before pressurizing - drives air out of the canner. Trapped air lowers the temperature below what your gauge implies, so skipping the vent means your food may be under-processed even at the correct pressure.

Only if it follows a tested recipe. Use only the ingredients and proportions from USDA or NCHFP tested recipes, keep solids at half the jar or less, and never add pasta, rice, noodles, dairy, flour, or other thickeners - they slow heat penetration and make published times unsafe.

USDA recommends using home-canned food within 1 year for best quality. Jars that sealed properly and are stored cool, dark, and dry remain safe beyond that as long as the seal is intact - but if a lid is loose, bulging, leaking, or the food looks or smells off, throw it out without tasting.

Salt is optional in pressure canning - 1/2 teaspoon per pint or 1 teaspoon per quart is for flavor only and does not affect safety. Lemon juice is different: crushed tomatoes must be acidified (2 tablespoons of bottled lemon juice per quart, 1 tablespoon per pint, or 1/2 teaspoon citric acid per quart) because their natural acidity is borderline.

Foods with pH at or below 4.6 are acid foods and can be water-bath canned; foods above 4.6 are low-acid and must be pressure canned. Clostridium botulinum cannot grow below pH 4.6, which is why the line matters. Most vegetables (pH 5.0-6.5), all meats, soups, and stocks are low-acid.

No. Use a new flat lid for every jar - the sealing compound is single-use. Screw bands (rings) can be reused as long as they are clean and undamaged. Always inspect jar rims for nicks before filling.

Liquid loss (siphoning) usually comes from cooling the canner too fast, fluctuating pressure during processing, or incorrect headspace. Let pressure drop to zero naturally and wait 5-10 minutes before opening the lid. Jars that sealed with at least half their liquid are safe; unsealed jars must be reprocessed within 24 hours or refrigerated.

No. This calculator implements published USDA process times and altitude rules for convenience, but it is not professional food-safety advice. Always cross-check against the USDA Complete Guide to Home Canning and your canner manufacturer's manual before processing food.