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Can You Put Cardboard in the Microwave?

Maria Foster
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by Maria Foster

You ate a delicious dinner the night before and took home a box of leftovers. Now, you’re ready to enjoy all the goodness that remains. So, you open up your fridge and take out the cardboard box. Obviously, you want to avoid dirtying another dish because who wants to do dishes? But you can’t help but wonder, “can you microwave cardboard?”

We promise you’re not the only one with this burning question. Countless others have considered the potential consequences of microwaving cardboard. Whether you’re just curious, too busy, or maybe a little too lazy to wash a dish or two, it’s still a good question.

When it comes to microwaves and food, you want to be apprehensive of any harmful aftereffects or fire hazards. At the end of the day, it’s always better to be safe than sorry. Keep reading to learn the answer to the question: is cardboard microwavable?

Related: Can You Put Pizza Cardboard in the Oven?

Can You Microwave Cardboard?


Can cardboard go in the microwave? Yes, it can. However, whether or not you should microwave your pizza box or takeout container depends on a few factors such as the temperature of your microwave oven, the type of cardboard, and if it has a plastic coating. Some standard cardboard containers include:

  • Pizza boxes
  • Take-out containers from restaurants
  • Disposable cups, plates, and bowls
  • Food packaging
  • Recyclable containers

Cardboard is made from tree material, similar to paper. And that means it’s flammable. That being said, it doesn’t imply that you should completely avoid heating it in your microwave. It typically takes a temperature higher than 400°F for cardboard to spark.

Related: How to Keep Pizza Warm

Helpful Tips When Microwaving Cardboard Containers

There are a few things you should keep in mind before reheating any type of cardboard. Consider the following tips the next time you want to microwave your takeout:

  • Read All Package Labels
    Lots of foods are packaged in specific cardboard, plastic, or paper containers. Many of these include an exterior label indicating whether or not the box is safe to microwave. Remember to check this label to ensure that you’re able to reheat it as is or switch to a microwave-safe dish.
  • Make Sure Food is in the Container
    This may seem like a no-brainer, but it’s important to note that cardboard should not be heated in the microwave alone. No matter if it’s a cup, plate, bowl, or box, there must be food within the cardboard container. Foods and liquids absorb the energy from the microwave as it heats up. If there’s no substance within the container and it’s heated to a high temperature of at least 400°F, it’s more likely to ignite.
  • Don’t Microwave For Extended Amounts of Time
    The longer your food is in the microwave heating, the more likely it is to overheat and potentially spark a flame. It’s best to put your food in for a minute or two at a time. Check it frequently as it’s cooking rather than letting it sit in there for many minutes.
  • Use Low Heat Setting
    As previously mentioned, you don’t want to heat your cardboard container (and the delicious food within) over 400°F. So we advise that you know your microwave’s wattage and use the lowest heat setting on your microwave when cooking your food in cardboard.
  • Line Your Container
    One way to protect your food in all cardboard-heating cases is to line the bottom of the container with a piece of parchment paper, a napkin, or a paper towel. It protects the food from direct contact with the cardboard bottom. It also prevents the oils in the food from getting onto the cardboard, which can be dangerous, as oils heat exceptionally quickly.
  • Avoid Adhesives and Inks
    Some cardboard containers may have writing on them, such as the name of the restaurant or brand. Others may have cardboard containers that were constructed using glue or another type of adhesive. These substances have chemicals in them that can be released when cooking in a microwave. So, it’s best to avoid heating them at all costs.
  • Avoid Coated Containers
    Coated cardboard can emit toxic fumes or start to melt in the microwave as it’s heating, contaminating your food, and probably ruining your microwave. This situation is usually rare, as there aren’t many cardboard containers with plastic or wax coatings on the outer layer of material. However, if you discover that yours has this coating, it’s best to settle for switching to glass, porcelain, or another microwavable dish.
  • Monitor Your Meal
    Never leave a microwave unattended while heating cardboard. You must keep a close eye on your container and food while you’re reheating to avoid any fires from starting. Be sure to stop the microwave and check the temperature of your food a couple of times during the heating process to prevent overheating.
  • Watch for Metal
    Some takeout containers and prepackaged foods can contain metal parts either inside or outside the box. It’s critical to make sure your container does not have any metal component in or on it, as metal is extremely flammable when heated and causes damage to yourself and your microwave.

Note: Sometimes recycled cardboard also contains metal particles, which can ignite within the microwave. However, this is generally uncommon.


Can you microwave cardboard? The simple answer is absolutely. However, we advise you to be careful and follow all the tips listed above to ensure you’re doing it safely each time as containers vary to restaurant and store.

It’s essential to make sure that your container remains intact and your food remains safe to eat. If you have any doubts about whether or not your cardboard container is safe to microwave, stay on the safe side and don’t do it. Just suck it up and get another dish.

Hopefully, after reading this article, you understand how to approach microwaving cardboard containers and can potentially avoid the annoying clean-up after your meal. Now the next time your friend orders a pizza and asks: “Can you put cardboard in the microwave?” You’ll know the answer and can enjoy eating it with them without worry. Happy heating and eating!

About Maria Foster
Maria Foster
Maria Foster is a mother of 3 and she and her husband of 23 years share their home with 2 faithful dogs. Besides being CEO of the household and active in her community, Maria is the lead contributor to Food Champs and loves to try new food ideas and kitchen accessories to make easier and more delicious meals.
Maria Foster
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