Can You Microwave Glass?
You're ready to chow down on delicious leftovers. But wait! Is it safe to microwave glass?
When it comes to reheating food in the microwave, you almost can’t go wrong with glass. Before warming up your meal, take a beat to check what type of glass you’re working with.
Can You Microwave Glass?
Yes, as long as the glassware is labeled “microwave safe.” This means the glass is designed to handle high temperatures. In most cases, plastic to-go containers aren’t microwaveable, nor are styrofoam containers, so reheating takeout is safest in a glass dish.
This also applies to other types of cooking—only glass marked “oven safe” should be used in the oven.
What kinds of glass can you not microwave?
Anything that’s not labeled “microwave-safe” (or doesn’t pass the microwave test below). That’s because the glassware could have metal, dyes or air bubbles that can cause the glass to crack or shatter in the microwave. You also want to avoid microwaving drinking glasses or glass food storage with a plastic seal. (Learn more about whether you can put plastic in the microwave.)
Can you microwave cold glass?
That depends. You’ve got the green light on glass that’s been recently refrigerated and is only slightly cold, but if it’s been in the fridge for a while or in the freezer, let the glass warm up on the counter first. Without thawing, the extreme heat fluctuations can cause the glass to crack or break, leading to a mess.
FYI: Here’s how to clean a microwave.
Tips for Microwaving Glass
How can I tell if glass is microwave-safe?
Microwave-safe glass will have a small image of a microwave with squiggly lines. However, some older glass might not have this symbol.
Editor’s Tip: Keep an eye out for microwave-safe symbols on anything you might be tempted to heat up! (Learn more about when you can microwave cardboard.)
Use the microwave test when in doubt
Follow this microwave test:
Fill your glass dish with a cup of cold water, then put it in the microwave for 1 to 2 minutes. Then, check its temperature. If the glass is hot to the touch, it’s not safe to use in the microwave. If it’s only slightly warm, or even cool, but the water inside is heated, the dish is likely microwave-safe.
Keep in mind that thin glass could crack during the microwave test. Proceed with good judgment.
When you heat up food, stir the contents throughout to make sure your food is warmed evenly and that heat is distributed. Find more microwave tricks every cook should know.
Keep it under 5 minutes
Glass is unlikely to melt in your microwave, but to make sure that it doesn’t crack or break, don’t leave it in the microwave for more than 5 minutes. (Learn more about when you can put aluminum foil in the microwave.)