This Is What the Symbols on the Bottom of Food Storage Containers Really Mean
I own a decent amount of kitchen appliances, but the one I use the most (and makes me the happiest) is easily my microwave. It’s at least partly because I lived in two different apartments with such limited counter space that I couldn’t even fit a microwave, so having one now is a feat in itself. Cooking is way easier and quicker with said microwave — however, the one thing that makes it tricky? Deciphering all those marks on my food storage containers and stoneware to figure out which of them is actually microwave-safe.
There are a surprising number of microwave-safe symbols you may find on containers and tableware — and just as many that denote that something isn’t microwave-safe. I spoke to experts and got into the nitty-gritty of figuring out which of these symbols mean it’s okay to pop your container in the microwave, and which ones don’t. Keep reading to find out how to know in an instant whether your cup or bowl will survive the microwave or not.
How to Tell if a Container Is Microwave-Safe
Simply put? It really does come down to that symbol on the container. “Typically, an item will have an icon or label indicating whether it is microwave-safe,” says Shirley Hood, an appliance expert at Abt. Before putting any containers in the microwave, take a look on the bottom to see whether it has such a symbol. More on decoding the different symbols below.
What if Your Containers Don’t Have Any Symbols?
Before you start saying “argh” and cursing the appliance gods, just breathe … and put your food into a different container. “If no label is present, it’s best to err on the side of caution and avoid using the item in the microwave,” Hood says.
What Are the Most Common Materials That Are Microwave-Safe?
There is actually a pretty wide range of materials that you can almost always guarantee are microwave-safe (even some plastic containers!). In general, you can safely microwave items made from these materials:
- Glass
- Ceramic
- Microwave-safe BPA-free plastics
- Food-grade silicone
- Some paper products (plates, napkins, wax, and parchment)
Are There Any Materials You Should Avoid Microwaving?
Conversely, there are plenty of items that you should never put in the microwave. “These materials may not withstand microwave temperatures, are flammable, can cause sparks, release toxic fumes into your food, or damage your microwave,” Hood says. Avoid microwaving these materials at all costs:
- Styrofoam
- Brown paper bags
- Non-microwave safe plastics
- Aluminum foil
- Metals
- Insulated mugs
What Happens if You Put Something in the Microwave That Isn’t Microwave-Safe?
The experts can’t stress this enough: Putting items in the microwave that don’t have microwave-safe symbols is likely cause for disaster. “Placing non-microwave safe items in the microwave can cause contents to catch fire, and items to melt, warp, or release harmful toxins into your food,” Hood says. “The bottom line is, it’s better to be safe than sorry if it isn’t labeled microwave-safe.”
What Are the Most Common Microwave-Safe Symbols?
Now that you know a little more about the types of items than can or can’t go in the microwave in the first place, it’s time to decipher those different symbols on your food storage containers and other tableware. Here’s a helpful guide to figure out the difference between microwave-safe symbols and ones to avoid:
Microwave-safe symbols
1. Wavy horizontal lines
There are different ways these lines may appear. It may show an image of a microwave, a dish set below the lines, or just the lines by themselves. No matter what, these wavy lines mean you can safely microwave the item.
2. Microwave icon with wavy lines
Just like those wavy horizontal lines, this is another microwave-safe symbol. Those same wavy lines will show up with a little microwave icon to show you that, yes, you can put it safely in the microwave.
3. Pan with wavy lines
Voilà, another icon with wavy lines! A pan with three squiggles shows that the item is microwave-safe.
4. “Microwave safe”
Some items will actually have these words printed on the bottom. If that’s the case, go ahead and microwave them.
Non-microwave-safe symbols
1. Wavy horizontal lines and an X
The wavy horizontal lines with an X through them mean exactly what you might assume — don’t put that container in the microwave.
2. Crossed out microwave icon
If you see a drawing of a microwave with a diagonal line through it, just consider that to be the icon saying, “Danger, danger!” Avoid microwaving that item.
3. “Not microwave safe”
Just like the “microwave safe” words above, some containers will feature the words “not microwave safe.” Just don’t do it. “This clearly signals that the item should not be used in a microwave,” Hood says.