How to Prevent Glass Food Storage Containers from Cracking in the Freezer

Freezing meals in glass food storage containers is a smart, eco-friendly habit, but it comes with one big worry: cracking. No one wants to open the freezer to find shattered glass and ruined dinner. The good news is that most cracks are avoidable if you understand how glass reacts to cold and follow a few simple rules.

Whether you're meal-prepping soups, stews, or casseroles, a little care goes a long way. In this guide, we'll walk you through the best practices for freezing in glass, explain why thermal shock happens, and show you how to choose containers that are built for the job.

Why Does Glass Crack in the Freezer?

Glass cracks in the freezer primarily because of thermal shock and the expansion of food as it freezes. Thermal shock occurs when a container experiences a sudden, extreme temperature change—like moving it directly from a hot oven to a cold freezer. The rapid contraction can create stress points that cause the glass to fracture.

Another culprit is overfilling. When liquid freezes, it expands by about 9%. If you fill a container to the brim with soup or sauce, the ice has nowhere to go, so it pushes against the glass walls. Over time, this pressure can weaken the container and lead to cracks, even if it's labeled 'freezer-safe.'

• Always cool hot food to room temperature before freezing.
• Leave at least an inch of headspace for liquids to expand.
• Use containers specifically designed for freezer use.

How to Freeze in Glass Containers Safely

To prevent cracking, start by letting your cooked food cool completely. Rapid temperature changes are the number one enemy of glass. Once the food is at room temperature, transfer it to your container, leaving enough space for expansion. Then, place the container in the refrigerator for a few hours before moving it to the freezer. This gradual cooling process minimizes thermal shock.

Another key step is to avoid stacking containers while they are still warm or partially frozen. Instead, place each container flat on a freezer shelf with space around it. This allows cold air to circulate evenly and prevents uneven freezing, which can stress the glass.

When you're ready to thaw, never place a frozen glass container directly into hot water or a hot oven. Instead, thaw it in the refrigerator or at room temperature. For reheating, transfer the food to a stovetop pot or use the microwave with a container that's labeled microwave-safe.

• Refrigerate filled glass containers before freezing.
• Freeze containers uncovered until fully frozen, then seal lids.
• Avoid sudden temperature changes when thawing or reheating.

Choosing the Right Glass Food Storage Containers

Not all glass is created equal. For freezer use, look for containers made from tempered glass, which is more resistant to temperature swings. The Misen 8-Piece Glass Food Storage Set includes a variety of rectangular and round dishes with airtight, leak-proof lids—perfect for freezing individual portions or family-sized meals. The square shallow dishes in the set are especially handy for stacking in the freezer, saving space without compromising safety.

If you often freeze smaller portions, the Misen 4-Piece Glass Square Dish Set offers versatile sizes that are great for leftovers and meal prep. For larger batches, the 10-Cup Glass Square Shallow Dish provides plenty of room for casseroles and stews, and its shallow design helps food freeze faster and more evenly, reducing the risk of ice crystals that can damage the glass.

Always check that the lids are freezer-safe too. The silicone and plastic lids on Misen containers seal tightly to prevent freezer burn, but they should be removed or loosened slightly during the initial freezing phase to allow air to escape and prevent pressure buildup.

• Choose tempered glass for better thermal resistance.
• Use shallow dishes for faster, more even freezing.
• Check that lids are freezer-safe and designed for airtight sealing.

Cracking in the freezer is almost always preventable. By cooling food properly, leaving headspace, and choosing high-quality tempered glass containers like those from Misen, you can freeze with confidence. Treat your glass containers gently, and they'll serve you for years—without a single crack.