How to Sterilize Canning Jars (3 Methods)

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Here's how to sterilize canning jars the tested way: set clean, empty jars upright on the rack in a canner, cover them with hot water by 1 inch, and boil for 10 minutes, adding 1 minute for every additional 1,000 feet above 1,000 feet. That's the method the National Center for Home Food Preservation (NCHFP) gives.

The bigger news is that you often don't need to sterilize at all. The NCHFP says jars only need sterilizing for foods processed less than 10 minutes in a boiling water canner, such as some jams, jellies and pickles. For anything processed 10 minutes or longer, or in a pressure canner, clean, hot jars are enough, because the processing itself sterilizes them.

Below are the three methods worth knowing: boiling-water sterilization, a hot wash-and-hold, and the dishwasher. We also cover why the oven method is unsafe.

How to Sterilize Canning Jars: First, Do You Need To?

Washing still matters every time. Even when you skip sterilizing, jars must be clean, rinsed well and hot when you fill them.

Method 1: Boiling-Water Sterilization (When Sterile Jars Are Required)

Use this for any recipe with a processing time under 10 minutes. It follows the NCHFP's "Sterilization of Empty Jars" directions.

1. Inspect the jars. Run a finger around each rim and discard any jar with nicks, cracks or chips.
2. Wash the jars in hot, soapy water and rinse them well.
3. Set the empty jars upright on the rack in a boiling water canner or a deep pot with a rack.
4. Fill the canner and the jars with hot (not boiling) water to 1 inch above the jar tops.
5. Bring to a boil and boil for 10 minutes if you're below 1,000 feet. Add time for elevation (see the table below).
6. Lift the jars out one at a time with a jar lifter, pour the water back into the canner and fill each jar while it's hot.
7. Save the hot water in the canner. The NCHFP says to use it to process the filled jars.
8. Add lids and bands and process right away.

Sterilizing time by elevation

The NCHFP rule is 10 minutes below 1,000 feet, plus 1 minute for each additional 1,000 feet:

If you don't know your elevation, your county extension office can tell you.

Method 2: Wash and Keep Hot (For Processes of 10 Minutes or More)

This is the method you'll use most. The jars don't need to be sterile because the processing time sterilizes them, but they do need to be clean and hot so they don't crack when hot food goes in.

1. Inspect each jar for nicks and cracks.
2. Wash in hot, soapy water and rinse well. Leftover detergent can affect the food.
3. Keep the jars hot until you fill them. Easy ways to do that: stand them in the canner while the water heats, or keep them in a pot of hot water.
4. Fill the warm jars with hot food, leave the headspace the recipe calls for, wipe the rims and put on lids.

The NCHFP says you can skip presterilizing for pressure canning, too. If you're processing vegetables, meat or beans, our guide to using a pressure canner picks up from this step.

Method 3: The Dishwasher (Wash and Hold Warm)

A dishwasher cleans jars and can keep them warm, but it doesn't sterilize them. NDSU Extension's Jar It Right! (FN2027) says you can use a dishwasher to wash jars and hold them warm and ready for canning. It also says sterilizing isn't required if the recipe's processing time is longer than 10 minutes.

1. Run the jars through a normal cycle with detergent, and check that they come out fully clean and rinsed.
2. Leave the door closed so the jars stay warm until you're ready to fill.
3. Take out one jar at a time as you fill it.

When sterile jars are required, the dishwasher isn't enough. Use Method 1.

Why You Shouldn't Sterilize Jars in the Oven

Oven sterilizing gets a lot of search traffic, but extension services say don't. University of California Cooperative Extension calls it a myth. It explains that canning jars are made from annealed glass that isn't designed for an oven's dry, fluctuating heat. That can cause thermal shock and cracked or even exploding jars, and a pan of water in the oven doesn't fix it. Its advice: sterilize jars in a boiling water or steam canner, and never bake in canning jars.

The NCHFP separately advises against processing filled jars in a conventional oven, a microwave or a dishwasher, saying those methods don't prevent all risks of spoilage. UC Cooperative Extension adds that heat moves into jars much more slowly through air than through water or steam.

Lids and Bands: What They Need

• Lids: University of Maine Cooperative Extension says the right way to prepare dome lids and bands is to wash them in warm, soapy water. That's it. It notes that Ball stopped recommending preheating lids about 10 years earlier, and that preliminary research suggests preheating may even cause lids to buckle. For other brands, follow the directions on the box. The NCHFP also says to follow the lid maker's preparation directions.
• New lids each time: dome lids are single-use for sealing. Our guide on whether you can reuse canning lids explains why.
• Bands: wash them, tighten them only fingertip-tight, and don't retighten after processing. The NCHFP says to remove bands once the jars have cooled.

Common Mistakes

• Sterilizing when you don't need to, then letting the jars cool. Cold jars can crack when you pour in hot food. Keep them hot.
• Skipping sterilization for a 5-minute jelly. Under 10 minutes, the jars must be sterile.
• Forgetting the altitude adjustment. Above 1,000 feet, add a minute per 1,000 feet.
• Oven-sterilizing jars. Extension services warn they can crack or explode.
• Assuming the dishwasher sterilizes. It washes and warms. It doesn't sterilize.
• Boiling lids. Not needed for Ball and Kerr lids, and it may cause buckling.
• Reusing chipped jars. A nick on the rim can stop a lid from sealing. The NCHFP says to check the sealing surface for tiny nicks whenever a jar fails to seal.

What You'll Need

• A boiling water canner or deep pot with a rack. Our canning pot guide compares them, and a steam canner is another option for acid foods.
• A jar lifter
• Clean dish towels or a rack for draining
• New lids and clean bands

Our canning supplies guide covers the full starter kit.

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