Can You Put Cardboard In The Oven?

Pizza gets delivered in big, flat cardboard boxes that are practically steaming with deliciousness. If you are waiting for someone before you eat or can’t get to your slice right away, you may be wondering can you put cardboard in the oven to keep it hot. 

Cardboard should never be put in the oven. It could ignite and cause a fire. In addition, many types of cardboard are made from recycled materials. They may contain adhesives, dyes, and chemicals—these could release toxic fumes or leach harmful substances into your food at high temperatures. 

Cardboard is a handy material that is useful as packaging. You will see it everywhere as it is cheap and sturdy.

One place you should never find a piece of cardboard is in the oven – let’s find out why. 

Can You Put Cardboard In The Oven? 

Cardboard is made by pressing and gluing layers of paper together.

It is created from the same wood pulp material as regular paper, just much thicker. 

Putting a cardboard box in the oven would be similar to putting a newspaper in the oven, and no one would ever consider that to be safe.

The cardboard on a smooth, shiny surface like a pizza box may feel slightly different from the rough cardboard roll inside a roll of paper towels, but the core material is the same, except it might have been coated with a waxy layer. 

The ignition temperature of paper and cardboard is relatively low.

That means there is a high chance that it can start burning even if your oven is set at a low temperature.

Besides possibly starting an even bigger fire, flames and smoke would ruin your food and make the house smell terrible when you open the oven door. 

But the risk of a fire is not the only reason you should avoid putting any cardboard into the oven.

You need to know some other things about cardboard before you combine it with heat. 

1. Heating cardboard may release toxic fumes

Cardboard is sturdy and thick because various chemicals and glue are often added to the paper pulp.

This is perfectly safe at low temperatures but turn up the heat, and the vapor rising from an innocent-looking cardboard box could be toxic. 

It is not only the actual cardboard that may have glue inside.

Many boxes, especially pizza boxes, have a thin coating of wax or plastic to prevent grease from seeping through the cardboard.

This additional layer was only intended to store and transport food effectively and should not be heated. 

2. Putting cardboard in the oven may make your food taste different

Even though you are only keeping something warm in the oven, anytime heat is applied to food, it is actually cooking, even if it is slowly.

Placing cardboard in the oven is, therefore, cooking it along with the food on it. 

The food on the cardboard may absorb some of the substances that the box is made from.

Of course, there are quite a few factors to consider, like how thick the cardboard is and how cheesy your pizza is.

The fact is that warm vapor from the cardboard is sure to combine with the outside of your food, which may give it a weird taste.

You may get a hint of glue or the flavor of the wood pulp that the box is made from on your food.

3. Cardboard can make food heat unevenly

Unlike aluminum foil which reflects heat and allows the outside of your food to heat evenly, the cardboard will act as a barrier to heat – or at least it will try to before it ignites.  

Pizza is put in boxes before being delivered because cardboard acts as a barrier to heat.

The heat from a freshly made pizza will get trapped inside the box, so your food will stay piping hot until it gets delivered.

If you put a pizza box in the oven, the outside of the box will heat up more than the food inside. 

Can You Put Cardboard In The Microwave?

Putting cardboard in a microwave is not recommended, but it is considerably safer than putting it in the oven.

This is because microwaving food is less likely to cause the paper component in the cardboard to heat up and ignite than if it is placed in a hot oven. 

If you are sure the cardboard you are using does not contain any plastic coating or color dyes, it can probably be microwaved.

For example, white paper plates can be used to reheat food in a microwave safely. 

If you have pizza on a plain cardboard surface, it probably can be reheated in the microwave if you use short bursts of heat and stand by to take your food out as soon as it has warmed up.

You must never put cardboard into the microwave that doesn’t contain food, as the cardboard itself will cook and will probably ignite when it gets hot enough. 

Be careful that the cardboard you put into the microwave doesn’t contain any waxy film or colorful inks that could melt or leach into your food. 

Another thing to look out for before popping cardboard takeout containers into the microwave to reheat them is to check that they don’t have any metal bits.

Sometimes Chinese takeout boxes have cute little metal handles, which would be unsafe to microwave. 

Can You Reheat Food In The Oven Safely? 

You can safely keep food warm or reheat items in the oven using oven-safe dishes or a baking tray.

Transfer any food you are reheating onto one of these safe surfaces before putting it into the oven.

Even if the oven is only on low heat, it is too dangerous to risk causing a fire, so make it a habit never to put cardboard into the oven. 

If you need a quick disposable covering for leftovers, use a piece of aluminum foil. This will also keep the moisture locked into your food, so it doesn’t dry out while reheating. 


It is not recommended to put any type of cardboard in the oven.

The risk of the material igniting is very high, which would be dangerous.

In addition, heating cardboard can release toxins that will cause hazardous fumes or alter the food’s taste.