About the Canning Altitude Adjustment Calculator
This canning altitude adjustment calculator tells you how to change a home-canning recipe for your elevation. Water boils at a lower temperature the higher you live — about 202–203°F at 5,000 ft instead of 212°F at sea level — so jars in a boiling-water canner need longer processing, and pressure canners must run at a higher pressure to reach the 240°F needed to destroy Clostridium botulinum spores in low-acid foods.
For pressure canning it applies the USDA rules published by the National Center for Home Food Preservation (NCHFP): a dial-gauge canner adds 1 psi for each 2,000-ft band (11, 12, 13 and 14 psi for most low-acid foods from sea level to 8,000 ft), and a weighted-gauge canner switches from 10 psi to 15 psi (or from 5 to 10 psi) above 1,000 ft. Processing time does not change in a pressure canner. For a boiling-water canner it adds time using the general altitude chart printed by jar makers and many Extension services: +5 minutes from 1,001–3,000 ft, +10 to 6,000 ft, +15 to 8,000 ft and +20 to 10,000 ft.
Only use recipes that have been scientifically tested (USDA, NCHFP, Extension or jar manufacturer). If your tested recipe includes its own altitude table, follow that table — USDA times are product-specific and the general chart here equals or exceeds them for the examples we checked. Never shorten a processing time and never water-bath low-acid foods such as vegetables, meat or beans.
How to use the canning altitude adjustment calculator
- 1Find your elevation (a map app, your county Extension office or a topographic map).
- 2Choose boiling-water bath or pressure canner, matching your tested recipe.
- 3For a water bath, enter the recipe’s processing time for 0–1,000 ft.
- 4For a pressure canner, choose the recipe’s sea-level pressure.
- 5Process for the adjusted time or pressure, starting the clock only once the water is boiling or the canner is at pressure.
Formula and method
Pressure-canner adjustments follow the USDA Complete Guide to Home Canning as published by NCHFP: dial-gauge recipes processed at 11 psi at 0–2,000 ft rise to 12 psi at 2,001–4,000 ft, 13 psi at 4,001–6,000 ft and 14 psi at 6,001–8,000 ft (6 → 7 → 8 → 9 psi for low-pressure fruit recipes). Weighted-gauge canners have fixed 5, 10 and 15 psi weights, so above 1,000 ft they move up one weight. Processing time stays the same.
Boiling-water processing time uses the general altitude chart: add nothing up to 1,000 ft, then 5, 10, 15 and 20 minutes for the bands ending at 3,000, 6,000, 8,000 and 10,000 ft. The boiling point is interpolated from the NCHFP table (212°F at sea level, 208°F at 2,000 ft … 194°F at 10,000 ft).
- h
- Elevation in feet (metres × 3.2808)
- t₀
- Recipe processing time for 0–1,000 ft
Worked examples
Applesauce quarts at 5,000 ft (water bath)
Applesauce quarts process for 20 minutes at sea level. At 5,000 ft (the 3,001–6,000 ft band) add 10 minutes for 30 minutes — exactly what the USDA applesauce table lists. Water boils at about 202.5°F there.
Green beans in a pressure canner at 3,500 ft
At 3,500 ft a dial-gauge canner must run at 12 psi instead of 11, and a weighted-gauge canner uses the 15 psi weight because the elevation is above 1,000 ft. Processing time (20 minutes for pints of beans) is unchanged.
Jam at 1,800 m
1,800 metres is about 5,906 ft, inside the 3,001–6,000 ft band, so a 10-minute jam recipe processes for 20 minutes under the general chart. If the tested jam recipe lists its own altitude times, use those.
Frequently asked questions
Why do you need to adjust canning for altitude?+
Water boils at lower temperatures as elevation rises — about 208°F at 2,000 ft and 201°F at 6,000 ft. Lower temperatures kill microorganisms more slowly, so boiling-water processing needs more time and pressure canners need more pressure to reach 240°F.
What pressure should I use for pressure canning at high altitude?+
For most low-acid foods a dial-gauge canner runs at 11 psi up to 2,000 ft, 12 psi to 4,000 ft, 13 psi to 6,000 ft and 14 psi to 8,000 ft. A weighted-gauge canner uses 10 psi up to 1,000 ft and 15 psi above that.
Do I increase the time in a pressure canner at altitude?+
No. In a pressure canner you increase the pressure, not the time — the higher pressure restores the sterilizing temperature. Process for the time stated in the tested recipe.
How much time do I add for water bath canning at altitude?+
Follow the altitude table in your tested recipe when it has one. As a general guide, add 5 minutes at 1,001–3,000 ft, 10 minutes at 3,001–6,000 ft, 15 minutes at 6,001–8,000 ft and 20 minutes at 8,001–10,000 ft.
Can I water-bath can vegetables if I process them longer?+
No. Low-acid foods such as vegetables, meats, poultry, seafood and beans must be pressure canned. A boiling-water bath can never reach the 240°F needed to destroy botulism spores, however long it runs.
This tool gives general estimates and is not medical advice. Talk to a doctor or qualified professional about your health, diet or training.