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Sometimes I daydream about what it must have been like to go shopping when there was only one choice for everything. When you could just buy a shirt without wondering if it was moisture-wicking or hand-wash only, or eggs without concerns about whether the chickens were farm-raised or free-range. Honestly, that sounds delightful to me. But alas, and perhaps for the better, we now have much more information and many more choices when deciding which foods to eat and which products to use.
Take food-storage containers. Turn them around or flip them over and you’ll likely find a row of little symbols, all of which tell you something about the material used to make the container and may influence your decision about whether you want to use it. There are a lot of different symbols—some with obvious meanings and some that are a bit more ambiguous. And that’s putting it nicely.
So we’re here to clear it all up with a guide to what these symbols actually mean, courtesy of Martin Bucknavage, a retired food safety and quality specialist. Read on to get the lowdown—and learn why this info is more important than you may realize.
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How important is it to pay attention to a food-storage container’s symbols?
When your personal safety is involved (which it is in some cases), it’s pretty important to listen to what these symbols are telling you. Ignoring some of them could potentially render your food inedible or dangerous to eat, while ignoring others could mean you’re missing out on an opportunity to make a choice that would support the environment.
But here’s where it gets weird: Despite the potentially high personal and societal stakes, these symbols aren’t very consistent. Except for the recycling symbol, which was created in 1970 and is used universally, and the food-safe symbol, which was created by the European Union and is an international regulatory standard, none of the other symbols on food-storage containers are standardized. In fact, most were created or added by marketing departments so that customers would know how to best use the products. Symbols that mean the same thing also tend to resemble one another but have slight differences, making it hard to keep track of what’s what.
Of course, that’s where we come in.
What do the symbols on food-storage containers mean?
Here are the most common ones, including what they look like and what they mean. You’re welcome in advance!
Food-safe
What it looks like: A wine glass and a fork next to each other.
What it means: “It indicates that the material used in the product is considered safe for food contact,” says Bucknavage. That means two key things. First, that there aren’t any contaminants left over from the manufacturing process on the surface of the container. And second, if you’re using the container regularly as it’s meant to be used, the material itself won’t become a source of toxins that could be transmitted to your food.
“It’s useful when containers don’t immediately appear to be food containers,” Bucknavage adds.
BPA-free
What it looks like: Usually, this one will just be the words BPA Free. Sometimes, it will be BPA in a circle with a diagonal slash across it.
What it means: “This indicates that the container does not contain Bisphenol A (BPA), a chemical used to make certain types of food containers but has been found to leach into foods, where it can potentially become a health concern, especially for infants,” Bucknavage says.
According to the Mayo Clinic, BPA exposure may harm the brains of fetuses, infants and children, while separate research has suggested a link between BPA and high blood pressure, type 2 diabetes and heart disease. In other words, you probably don’t want it in the containers, dishes and cups you and your family use regularly.
Microwave-safe
What it looks like: Three horizontal wavy lines by themselves or inside a square meant to look like a microwave.
What it means: This one is pretty self-explanatory—it means you can safely put the container, with food in it, into the microwave for normal heating. “Not only should the container not melt or shatter, but there should not be chemical migration from the container itself,” Bucknavage says.
Freezer-safe
What it looks like: A snowflake inside a square, sometimes with a little drawing of a freezer.
What it means: The container will effectively protect food when put in the freezer. “The material is designed to withstand freezing temperatures without becoming brittle or cracking,” Bucknavage says.
Dishwasher-safe
What it looks like: A square with dishes at the bottom and water droplets coming down on them.
What it means: In short, that you can put the container in the dishwasher. To get a bit more technical, it means that the container can withstand the high temperatures of the dishwasher and any chemicals in your dish soap without warping or breaking.
Compostable
What it looks like: Leaves with the word compostable or BPI, or a compost pile that looks sort of like a cupcake with arrows around it.
What it means: “This indicates that the food-packaging material will break down into organic matter in a specific composting environment,” says Bucknavage. Per the U.S. Department of Agriculture, composting is the process of recycling organic materials into something that can be used to enrich soil and plants. If you compost at home, this symbol means you can add the container to your bin when you’re finished with it.
Biodegradable
What it looks like: A triangle made up of two arrows and one leaf, or this symbol inside a circle that says biodegradable or eco-friendly.
What it means: The material the container is made out of will eventually break down into simple, natural substances, explains Bucknavage. How is this different from the compostable designation? Something with a compostable symbol requires a composting environment, while the biodegradable symbol theoretically means the material will just break down on its own.
“The issue here is that there are questions about the time frame, the conditions in which the item will break down and whether any problematic materials are left,” Bucknavage says.
Recyclable
What it looks like: A triangle made of arrows with a number in the middle and a few letters beneath.
What it means: This symbol tells you if the type of plastic used in the container is able to be recycled. “Some are more apt to being recycled, like numbers 1 and 2, while others are rarely accepted or not accepted,” says Bucknavage. “You should be aware of what your recycling center accepts.”
Here’s what all the numbers and letters mean, per the U.S. Department of Energy.
- 1 PET: Polyethylene terephthalate, a very common and easy-to-recycle plastic found in water and soda bottles as well as prepared- and frozen-food containers.
- 2 HDPE: High-density polyethylene, another widely accepted plastic found in household cleaner bottles, cutting boards and some food containers.
- 3 V: Polyvinyl chloride, PVC, which is found in toys and bottles and is harder to recycle.
- 4 LDPE: Low-density polyethylene, a soft type of plastic used in thin plastic bags that’s typically accepted for recycling at grocery stores.
- 5 PP: Polypropylene, found in straws, cups and food containers, and usually able to be recycled.
- 6 PS: Polystyrene, aka Styrofoam, usually found in takeout containers and disposable cups, and generally not accepted in recycling programs.
- 7 Other: This includes BPA, polycarbonate and bio-based plastics—all tricky to recycle.
- 70 GL: Mixed glass, which can be recycled.
- 71 GL: Clear glass, which can be recycled.
- 72 GL: Green glass, which can be recycled.
- 20 PAP: Made of at least 75% cardboard and can be recycled.
- 21 PAP: Made of at least 75% plain paper and can be recycled.
- 22 PAP: Made of at least 75% mixed paper and can be recycled.
Which is the most important symbol?
“I think the ones indicating where the container can be used are most important in an immediate sense,” says Bucknavage. “When not properly adhered to, it can result in breakage like shattering, which could result in physical injury.”
If you want to put your container in the microwave, dishwasher or freezer, make sure that the appropriate symbol is present. Ignoring these could cause the most problems in the short-term.
What else should you keep in mind about food-storage containers?
While the microwave-, dishwasher- and freezer-safe symbols are super important to abide by, all of the symbols outlined above can help you make healthy choices. Here are a few additional considerations to keep in mind when choosing and using food-storage containers.
- Use the symbols to reduce waste. “Packaging waste is a huge issue,” says Bucknavage. “Whether it can be recycled or composted needs to be a concern for everyone.” Before even checking the symbols on your containers, make sure you know which plastics can be recycled in your town and, if you don’t compost at home, if there is a commercial composting center you can take those containers to. The environment will thank you.
- Keep BPA away from babies. “BPA-free is especially a concern when we are using containers for infants and small children,” Bucknavage says. If you’re buying bottles, cups, dishes and food containers for little ones, choose BPA-free or glass whenever possible.
- Consider ditching plastic altogether. “With concerns around microplastics getting into our foods, many are moving to glass or ceramic containers,” says Bucknavage. Indeed, scientific research has linked microplastics—teeny-tiny bits of plastic that can enter the body through ingestion, inhalation and even skin exposure—to a higher risk of heart attack and stroke. We’re still learning about how much damage microplastics can actually cause, but if you want to switch to glass or ceramic food-storage containers to limit your exposure, it’s definitely not a bad choice.
Sources:
- Martin Bucknavage, food safety and quality specialist; email interview, July 2026
- Mayo Clinic: “What is BPA? Should I be worried about it?”
- U.S. Department of Agriculture: “Composting”
- U.S. Department of Energy: “Consumer Guide to Recycling Codes”
- The New England Journal of Medicine: “Microplastics and Nanoplastics in Atheromas and Cardiovascular Events”
