Canning Calculators

Processing times, brine ratios, headspace and altitude corrections. 10 calculators for home preserving. Fermented pickles sit under Pickling.

Altitude adjustment is a safety matter rather than a quality one. Water boils cooler as you climb, 94°C at 1,800 m against 100°C at sea level, and canning depends on reaching a temperature that kills Clostridium botulinum spores. A weighted gauge canner only offers 10 and 15 pounds per square inch (PSI), so above about 1,000 feet the answer is always 15. A dial gauge steps up more gently, from 11 PSI near sea level to 15 above 8,000 feet.

Headspace varies by process, not by preference. Jams take 6 mm because they barely expand. Fruits and pickles take 13 mm. Low-acid vegetables and meats need a full 25 mm, since pressure canning at 116°C drives much harder expansion. Too little and the jar boils over and never seals. Too much and the vacuum never forms.

Brine, syrup and pectin ratios here are by weight, and salt is where that matters most. A cup of coarse pickling salt and a cup of fine table salt hold very different amounts of salt, so a recipe measured by volume drifts by a third depending on which box you reached for.

Follow tested USDA (United States Department of Agriculture) times. This is not a category to improvise in.