Cooking Tips

How Altitude Affects Canning

When it comes to canning, your altitude affects boiling time and, ultimately, safety. Here's a chart to follow when making jams, jellies, preserves, or chutneys at any altitude.

Published May 8, 2017.

The boiling point of water decreases as altitude increases, which means that when canning at higher elevations you must process food longer in a boiling water canner. At sea level, the temperature of boilingw ater is 212 degrees Fahrenheit. The boiling point of water drops 2 degrees for every 1,000-foot increase in elevation. The altitude of America's Test Kitchen in Brookline, Massachusetts, and where we developed all of our recipes, is 50 feet, or basically sea level. To determine your elevation, you can Google the altitude of where you live, go to the website, or download a free smartphone app such as My Altitude.

Height (ft) Above Sea LevelMinutes Added to Processing Time



1,001-3,000 feet


3,001-6,000 feet


6,001-8,000 feet






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Foolproof Preserving

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