Canning Processing Time Calculator

At higher altitudes, water boils at a lower temperature because atmospheric pressure is reduced. Since boiling water bath canning relies on the heat of boiling water to destroy microorganisms, lower boiling temperatures mean less effective heat penetration — so additional processing time is required to ensure food safety. Above 1,000 feet, you must add time to compensate.

USDA guidelines recommend adding 5 minutes for altitudes of 1,001–3,000 ft, 10 minutes for 3,001–6,000 ft, 15 minutes for 6,001–8,000 ft, and 20 minutes for 8,001–10,000 ft. These adjustments apply on top of the base processing time listed in tested recipes.

For pressure canning, you adjust the pressure rather than the time. At higher altitudes, you must increase the PSI to achieve the internal temperature needed to destroy Clostridium botulinum spores. Dial gauge canners require incremental pressure increases; weighted gauge canners should be switched to 15 PSI above 1,000 feet.

Yes. Quart jars require longer processing times than pint jars because heat takes longer to penetrate to the center of a larger volume of food. Always use the processing time specified for your jar size in a tested recipe — never assume the time for a smaller jar is safe for a larger one.

Hot pack means you heat the food before loading it into jars, which allows you to fit more food per jar and often results in better color and quality. Raw pack means food is placed into jars unheated. Raw-packed foods generally require longer processing times than hot-packed foods because they start at a lower temperature.

No. Low-acid foods such as vegetables, meats, poultry, and fish must be processed in a pressure canner. Boiling water bath canning does not reach the temperatures needed (240°F / 116°C) to destroy Clostridium botulinum spores in low-acid foods, making it unsafe. Only high-acid foods like fruits, pickles, jams, and tomatoes with added acid are safe for water bath canning.

Headspace recommendations vary by food type: jams and jellies typically need ¼ inch, fruits and tomatoes ½ inch, and most vegetables and meats 1 inch. Correct headspace is critical for a proper vacuum seal — too little can prevent sealing; too much can cause discoloration or seal failure.

You can find your elevation using a GPS device, a mapping app like Google Maps (click your location and check coordinates/elevation), the USGS National Map website, or by contacting your local county extension office. Even a few hundred feet can make a difference, so use as accurate a figure as possible.