Canning at altitude: adjusting time and pressure

Just want the number? Enter your altitude in the canning altitude calculator for the water-bath minutes to add and the pressure PSI (dial & weighted) — free, never rounded down.

Water boils at 212°F at sea level, but the boiling point drops about 1°F per 500 feet of elevation. Cooler boiling water means less lethality — so USDA processes compensate two different ways depending on the method. (What people search for as an "altitude canning chart" or "elevation chart" is really these two tables — one for water-bath time, one for pressure-canner PSI.)

Water-bath canning: add time

For boiling-water-bath processing, USDA increases the processing time as altitude rises:

(These are the USDA increases for processes of 20 minutes or less; some recipes specify their own altitude adjustments — follow the recipe.)

Pressure canning: raise the pressure

For pressure canning, the time stays the same but the pressure (PSI) goes up with altitude — and the table depends on whether you have a dial gauge or a weighted gauge:

(Values shown are the common USDA pressures for many low-acid foods processed at "10/11 psi" at sea level; some recipes start at a different base pressure. Always use your recipe's numbers.) See it applied to a real food: pressure canning green beans — time & PSI by altitude.

How to find your altitude for canning

Look up your elevation by address with a topographic map, a phone GPS or altimeter app, or your county extension office, then use the bracket your elevation falls into on the chart above. Being off by one bracket can under-process your food, so confirm it before you start.

FAQ

How much time do I add for water-bath canning at altitude?
For boiling-water-bath processes of 20 minutes or less, USDA adds 5 min at 1,001–3,000 ft, 10 min at 3,001–6,000 ft, 15 min at 6,001–8,000 ft, and 20 min at 8,001–10,000 ft. (USDA/NCHFP.)

What pressure should I use for canning at altitude?
Pressure rises with elevation. A dial gauge runs ~11 psi to 2,000 ft, 12 psi to 4,000 ft, 13 psi to 6,000 ft, 14 psi to 8,000 ft. A weighted gauge uses 10 psi to 1,000 ft, then jumps to 15 psi above that.

How do I find my elevation for canning?
Look up your elevation by address with a topographic map, a phone GPS/altimeter app, or your county extension office, then use the bracket it falls into on the charts above. Being off by one bracket can under-process your food.

Is the altitude chart the same for green beans and tomatoes?
The altitude rules are the same, but they apply to each food's own base process — green beans raise PSI (pressure canning), while acidified tomatoes add water-bath minutes. Always start from your food's tested recipe.