Canning Altitude Calculator

Choose your canning method, set the unit, and enter your elevation. For boiling-water canning, add the processing time your recipe gives at sea level and the calculator returns the adjusted time along with the minutes it added. For pressure canning, pick the pressure the recipe calls for at sea level and it returns the pressure to run at your elevation.

The altitude tier is shown alongside the result so you can see which band you fall into and how close you are to the next step up. If you sit near a boundary, round upward — the tiers are conservative for a reason, and there is no penalty for a slightly longer process or a slightly higher pressure.

Water bath, 20 min recipe at 4,000 ft → 30 min

Weighted gauge, 10 psi recipe at 4,000 ft → 15 psi

Dial gauge, 11 psi recipe at 4,000 ft → 12 psi

Water boils at 212°F at sea level, but only around 202°F at 5,000 feet. A boiling-water canner cannot get hotter than whatever boiling is where you stand, so as you climb, the heat driving into the centre of the jar is weaker. Tested recipes assume sea-level boiling, which is why every canning chart carries an altitude column.

A pressure canner sidesteps the problem by trapping steam and raising the internal temperature above boiling. But the gauge measures pressure above the surrounding air, and the surrounding air is thinner up high — so the same gauge reading produces a lower temperature. Raising the pressure setting puts the temperature back where the recipe expects it.

Boiling-water canning is for high-acid foods — fruit, jams and jellies, pickles, and properly acidified tomatoes. The adjustment is purely a matter of minutes, stepping up through four tiers above 1,000 feet. Below that, use the recipe as printed.

A few practicals matter as much as the number. Start counting only when the water reaches a full rolling boil, keep it boiling for the whole process, and make sure the jars stay covered by at least an inch of water. Topping up with boiling water rather than cold keeps the process from stalling.

On a pressure canner the processing time never changes with altitude — the pressure does. A weighted gauge only offers fixed settings, so a recipe written for 10 psi at sea level steps straight up to 15 psi as soon as you are above 1,000 feet. There is no in-between to aim for.

A dial gauge reads actual pressure, so it climbs a pound at a time: 11 psi up to 2,000 feet, then 12, 13, 14, and 15 psi through the higher tiers. Recipes written for the lower 5 psi weighted or 6 psi dial settings shift up the same way. Have a dial gauge tested each season, since a gauge reading high means every jar is quietly under-processed.

Guessing is the one shortcut worth avoiding, because guessing low means under-processing. Look your address up on whatismyelevation.com or the USGS National Map, or ask your county extension office — many publish the elevation for each town precisely because canners keep asking.

Use the elevation of where you are canning, not the nearest city centre. In hilly country a few miles can move you a full tier, and if you land close to a boundary, treat yourself as being in the higher band.

Adjusting for altitude only works within a tested process. Low-acid foods — plain vegetables, meat, poultry, fish, soups — require a pressure canner at every altitude, and no amount of extra time in a boiling-water canner substitutes for that. The temperature simply never gets high enough.

The published tables also stop at 10,000 feet. Above that there are no tested processes to extrapolate from, so contact your local extension service rather than scaling the pattern upward. And always start from a tested recipe: the altitude adjustment corrects a known-good process, it does not rescue an improvised one.