Why canning depends on elevation
Canning is safe because heat kills the organisms that spoil food, and the heat has to reach a set temperature for a set time. In an open pot, the highest temperature water can reach is its boiling point, and that falls as you go up: about 212°F at sea level, around 203°F at 5,000 feet and around 194°F at 10,000 feet. Roughly, you lose 1°F for every 500 feet.
A water bath at 203°F delivers less heat than one at 212°F, so tested recipes make up for it with extra time. A pressure canner raises the boiling point by raising the pressure, and at higher elevations it needs more pressure to reach the same 240°F that makes low-acid foods safe.
Your elevation is the elevation of your kitchen. Tap Find me on our elevation page at home, or type your address into the elevation finder.
Boiling water bath: extra processing time
Water bath canning is for high-acid foods such as most fruits, jams, jellies, pickles and acidified tomatoes. Many USDA-tested recipes use the increments below, but some list their own times for each elevation band. Always use the table printed with your tested recipe when it has one.
| Your elevation | Add to the sea-level processing time |
|---|---|
| 0 to 1,000 ft | No change |
| 1,001 to 3,000 ft | 5 minutes |
| 3,001 to 6,000 ft | 10 minutes |
| 6,001 to 8,000 ft | 15 minutes |
| 8,001 to 10,000 ft | 20 minutes |
Pressure canning: more pounds of pressure
Low-acid foods such as vegetables, meat, poultry, beans and soups must be pressure canned. The processing time stays the same at any elevation; the pressure changes. Which column applies depends on your canner's gauge.
| Your elevation | Weighted gauge | Dial gauge |
|---|---|---|
| 0 to 1,000 ft | 10 lb | 11 lb |
| 1,001 to 2,000 ft | 15 lb | 11 lb |
| 2,001 to 4,000 ft | 15 lb | 12 lb |
| 4,001 to 6,000 ft | 15 lb | 13 lb |
| 6,001 to 8,000 ft | 15 lb | 14 lb |
| 8,001 to 10,000 ft | 15 lb | 15 lb |
Dial gauges drift. Have yours tested every year; many county extension offices do it free or for a small fee.
Sterilising jars at altitude
Jars for recipes processed for less than 10 minutes in a water bath need to be sterilised first. The standard method is to boil them for 10 minutes at sea level and add 1 minute for each additional 1,000 feet of elevation. Recipes processed for 10 minutes or longer sterilise the jars during processing.
Rounding and borderline elevations
If your elevation is close to a boundary, use the higher band. At 2,980 feet, follow the 3,001 to 6,000 feet row. The extra time or pressure costs a little texture at most; too little can leave food unsafe.
Elevation can change a lot over short distances in hilly country. If you live on a slope or moved recently, check your own address rather than your town's published elevation, which is usually measured at one point downtown.
These adjustments come from the USDA Complete Guide to Home Canning and the National Center for Home Food Preservation. When a recipe and this page differ, follow the tested recipe.