How to Sterilize Canning Jars
Wash jars in hot soapy water, then sterilize by boiling them in water for 10 minutes (add a minute per 1,000 feet above 1,000 feet altitude). For recipes processed 10 minutes or longer, jars are sterilized during processing, so they only need to be hot and clean.
When you need to sterilize
Jars must be sterilized when the recipe is processed for less than 10 minutes. For recipes processed 10 minutes or longer (and all pressure-canned foods), the jars are sterilized during processing, so they just need to be clean and hot when filled.
How to sterilize
Wash jars in hot, soapy water and rinse. To sterilize, put them right-side up on a rack in a large pot, cover with water, bring to a boil and boil for 10 minutes. Add one minute for each 1,000 feet above 1,000 feet of altitude. Keep the jars hot until you fill them.
Lids and bands
Follow current guidance for lids: most modern flat lids do not need boiling, just a wash in warm water. Always use a tested recipe from a trusted source such as the National Center for Home Food Preservation.
Frequently asked questions
Do I always need to sterilize canning jars?
No. Only for recipes processed under 10 minutes. Foods processed 10 minutes or longer, and all pressure-canned foods, sterilize the jars during processing, so clean, hot jars suffice.
How does altitude affect sterilizing jars?
Water boils cooler at altitude, so add one minute of boiling per 1,000 feet above 1,000 feet to make sure the jars reach a sterilizing temperature.