Perhaps you’ve seen videos of people burning cardboard in the microwave. Can you microwave cardboard? Is this safe? We’ll provide safety advice for microwaving cardboard in this article along with more information on why you should stay away from it at all costs.

While some cardboard can be microwaved without issue, care must be taken. Wax, glue, and other substances that can be hazardous when heated can be found in cardboard. Some packages also include fire-starting metal handles or staples. Only cardboard that is specifically labeled as microwave-safe.

Can Cardboard Be Microwaved?

The science behind whether or not cardboard is safe to use in a microwave oven can be unclear. It is both a good and a bad idea in the eyes of many experts, which is why. 

The rationale behind the good idea is that since paper plates can be microwaved without any issues, cardboard can also be heated in the microwave without any issues. Considering that both of them are made of paper.

You must typically believe that microwave cooking cardboard boxes and paper is dangerous if you consider how frequently they are used as simple, quick ways to start fires. However, the issue is not as severe as first appears because of how the microwave operates.

Food typically contains water molecules, and when you microwave it, these water molecules begin to move at a relatively high frequency. Friction created by this idea is what causes the food to heat up. 

Since cardboard boxes are disposable and do not contain a lot of water, there is no need to be concerned. It won’t warm up any quicker than the food, therefore.

Concerned about the amount of moisture the cardboard will absorb? Despite being absorbed by the cardboard, the steam rising from the food on top won’t reach high enough temperatures to start combustion.

This does not imply that all cardboard can be heated in a microwave. Prior to microwaving cardboard, keep some things in mind, like looking for the “microwave safe” symbol and only using it briefly. 

Furthermore, refrain from heating the cardboard more than once.

When Is Microwave Use Of Cardboard Not Recommended?

Although cardboard is generally safe to use in the microwave, there are still some situations where it’s not advised.

In order to ensure that a container is safe to microwave, you should always check the label. The majority of the remaining points I’m going to list will be satisfied by that. Never put anything in the microwave if it isn’t specifically labeled as being safe.

Next, never microwave cardboard by itself and only use it for brief periods of time. Even though your cardboard is unlikely to catch fire, the shorter the time, the better. You need food in the microwave with the cardboard to absorb the waves.

The materials used to make cardboard are frequently recycled. As a result, there’s a chance that your cardboard contains trace amounts of dangerous materials that you shouldn’t microwave, like metal. This is the reason it’s crucial to always read the label on your container.

You definitely don’t want to put metal-containing containers in your microwave, speaking of unsafe materials. The most prevalent kind of container in this category would be the kind you typically get from a Chinese takeout establishment, which usually have metal handles.

Can You Reheat Food In A Cardboard Box?

You can, in fact, reheat food in a cardboard box, but only in moderation. As a result, only a brief period of time can be spent reheating. 

Because cardboard is a relatively quick conductor of fire and can easily catch fire, prolonged heating may result in the cardboard box catching fire. Cardboard or corrugated board typically ignites a fire when exposed to an open flame and/or spark.

Despite this, the microwave oven is used to operating at lower heat levels than the point at which cardboard ignites, so the risk of cardboard burning while reheating food isn’t particularly high. 

Additionally, cardboard boxes are made from pure pulp and wood fiber, further enhancing their suitability for microwaving food.

As an alternative, cardboard may contain traces of metal to ensure that the pieces are secure and prevent leakage of liquid. Heating cardboard boxes can be harmful in these situations. 

The general rule is to avoid heating food in a cardboard box for an extended period of time. Because cardboard boxes can contain up to 12% moisture, the water level will begin to decrease when the box is heated. 

The level falls to 1% and below in this situation. If the pulp or fiber dries out too much, the result makes it easy to catch fire.

Do Cardboard Pizza Boxes Microwave Well?

One of the most delectable pleasures in life is leftover pizza. Obviously, unless you have the largest microwave in the world on hand, you cannot microwave the entire 18-inch pizza box.

However, what if you only need a small portion of the box or want to use a piece of it as a plate?

Since cardboard pizza boxes typically don’t have any plastic or wax coatings or metal fasteners, you can definitely microwave them in that situation. 

You won’t get a piping hot plate and a cold pizza because cardboard is porous and frequently doesn’t get as hot as your regular plates and bowls. 


Mcdonald’s Burger Boxes Can They Be Microwaved?

You might wonder if you can microwave the McDonald’s burger box it came in if you weren’t able to finish it and want to reheat it before digging back in. 

McDonald’s burger boxes are safe for the microwave because they are made of cardboard and don’t have any metal fasteners, plastic coatings, or wax linings. 

Remember, double check in case the boxes change over time, but generally, a The McDonald’s burger box is safe to microwave. To be safe, avoid heating it for an excessively long time. 

Cardboard Paper Plates Can Be Microwaved?

Paper plates are very handy, whether you’re entertaining guests or just don’t feel like doing the dishes after dinner. Can you microwave paper plates made of cardboard though? 

You can put a regular cardboard paper plate in the microwave without any issues if it is free of any plastic or wax coatings.

Cardboard doesn’t warm up nearly as quickly as the food you are heating because it has a low moisture content.

Due to its low moisture content, it won’t overheat or catch fire in the microwave. 

Things To Know About Microwaving Cardboard

You can’t microwave all cardboard boxes. Here are some considerations to make when microwave-safe containers are used with cardboard.

  • Checking the label: You might find the label with information about whether microwave cooking is risky if the container is a cardboard pizza box. A small three-wave icon indicating microwave safety should always be looked for. If the microwave icon is not present, you might want to look for written instructions.
    On each food-safe cardboard container, there will be a section with instructions that will explain how to heat your meal in the oven, stove, and microwave.
  • Check for metal: The presence of metal traces in some cardboard makes it unsuitable for microwave use. Check to confirm that harmful traces like aluminum foil are absent from the packaging.
  • Chemicals: It is best to stay away from soup bowls, cups, and containers that have waxy or plasticized coatings. Any type of Styrofoam insulation and cardboard boxes with printed ink must adhere to this principle. The additional parts could melt or emit hazardous fumes, which could contaminate your food with potentially harmful chemicals.
  • Microwave temperature: When heating a meal in a cardboard box, check the appliance’s settings and set the lowest setting possible. When using cardboard to reheat food, generally set your microwave’s temperature to the low power setting.
  • Type of food: Meals with a lot of water should not be heated because, if the box is closed, heat is produced and radiates relatively more slowly. An explosion will result from the buildup of pressure inside a closed container. The integrity of the cardboard material may also be compromised by heated liquid, which could cause it to become soggy and possibly degrade.


While some cardboard containers cannot be used in the microwave, many can. You may reheat your food as long as you’re utilizing a container made of microwave-safe cardboard.

Just be aware that there are instances when it makes no sense to put cardboard in the microwave, and in those cases, specific safety measures must be taken. Why not take advantage of this when your food is in containers? Microwaving food on cardboard is a quick, inexpensive alternative to using reusable plates.