How Altitude Affects Canning
When it comes to canning, your altitude affects boiling time and, ultimately, safety. Here are guidelines to follow when making jams, jellies, preserves, or chutneys at any altitude.
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 boiling water 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 Boston, Massachusetts, and where we developed all of our recipes, is 50 feet, or basically sea level.
Height Above Minutes Added to
Sea Level Processing Time
0-1,000 feet 0
1,001-3,000 feet 5
3,001-6,000 feet 10
6,001-8,000 feet 15
8,000-10,000 feet 20
10,000+ feet 25
