Freezing in Glass (Safety, Best Practices, Alternatives)

This article is about how to avoid shattered jars and freezer fails—straight from my kitchen to yours.

Freezing food in glass jars—especially mason jars—is totally doable. I’ve done it for years, and while it can be a little nerve-wracking the first time (yes, I’ve had one explode), it’s safe if you take a few smart precautions.

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Freezing in Glass – Best Practices

Glass is non-toxic, reusable, and doesn’t absorb flavors—so it’s a great option for storing soups, sauces, smoothies, and more. But not all glass is created equal, and there are some rules you’ll want to follow.

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📏 Headspace Matters: Leave Room to Expand

Liquids expand as they freeze—about 9% more volume than when they’re liquid. If there’s nowhere for that pressure to go, the glass breaks.

Anne’s Rule of Thumb:
Leave 2 to 3 inches of headspace between your food and the lid (closer to 3 inches for soups or broths).

Other smart tips:

• Use wide-mouth jars (no shoulder to catch the expanding liquid).
• Don’t screw the lid on tight until the contents are fully frozen.

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📦 How to Prevent Breakage in the Freezer

• Cool it first: Never freeze hot food in glass. Let it cool to room temperature before freezing.
• Avoid sudden temperature changes: No boiling hot liquids into cold jars. And don’t pull jars straight from freezer to hot water or oven.
• Space them out: Jars bumping into each other is a recipe for disaster. Either:
  • Use a cardboard divider box
  • Wrap each jar loosely in cloth or a paper towel
  • Place jars a few inches apart

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🕒 How Long Can You Freeze Food in Glass?

Just like other containers, glass can preserve food in the freezer for up to 12 months—depending on what you’re storing. Check out our freezer shelf life chart for specific food timelines.

💡 Tip: Label each jar with the name and date using painter’s tape or dissolvable labels. For even better organization, see: How to Label Frozen Food (And Actually Keep It Organized).

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🔄 Best Alternatives to Glass

If you don’t have room for jars—or are freezing in a rush—here are some solid alternatives:

• Silicone freezer trays: Perfect for sauces, broths, and smoothies in small portions
• Freezer bags: Use heavy-duty or double bag, lay flat for space-saving
• Plastic freezer-safe containers: Lightweight, stackable, and good for batches

See: The Best Containers for Freezing Every Type of Food

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🚫 What Not to Do

• Don’t fill glass all the way to the top
• Don’t use random recycled jars for freezer storage
• Don’t expose glass to sudden heat or cold
• Don’t stack jars directly on top of each other unless separated

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Final Thoughts

Freezing in glass isn’t just possible—it’s a great way to reduce waste and avoid plastics in your food. As long as you plan for expansion, avoid temperature shocks, and leave enough space between jars, you’ll be just fine.

For more tips, don’t miss:

• Freezing in Glass (Safety, Best Practices, Alternatives)
• How to Prevent Freezer Burn (And Still Eat What’s Salvageable)
• The Best Vegetables to Freeze (And Which Ones You Shouldn’t)

Thanks for stoppin’ by!
– Anne

🔗 For more: Don’t miss my comprehensive article on Freezing Food the Right Way | A Complete Guide to Portioning, Packaging, and Preserving.