Can You Put Cardboard and Pizza Boxes in The Oven?
Can you put pizza boxes and other cardboard in the oven to reheat your food? Is it safe? What are the risks? Or, how can I reheat my food?
Last night’s pizza is cold and you think it would be simpler to throw the whole cardboard pizza box in the oven to warm it instead of dirtying a cookie sheet.
Table of Contents
Will cardboard burn?
What else is in the box?
Frozen pizza bases
How to reheat pizza and food
Why would I want to reheat with cardboard?
Maybe you are having people over and want to keep the pizza warm until everyone arrives, even your friend who is always late.
Do you have some chicken nuggets in cardboard containers that you picked up on the way home from the game that you want to warm up? You know the microwave will make them soggy and rubbery.
We all have reasons to be tempted to put cardboard in the oven, pizza or not. For the majority of people thinking about this, it is the pizza box more often than anything else.
Short answer: No, you really should not put any cardboard in a hot oven. High temperatures and paper products do not play well together.
Will the cardboard burn?
Yes, the risk of fire is real if you put that cardboard in the oven. The book Fahrenheit 451 made the burn temperature of paper memorable. However, sources suggest the ignition point is somewhere between 425*F and 475*F. The thickness and moisture level of cardboard boxes varies which can lower the ignition point.
If it doesn’t burn, it could smoke and it would not be that nice wood-smoke smell. When that chemically smell gets into the pizza, it does not taste good. The smell will fill your kitchen and you will have nothing to eat.
The age of your oven is also something to factor in as well. Newer ovens are safer as the heating elements are covered and the heat is more even. Older ovens have exposed heating elements that you have to be more careful about direct contact with your oven mitts, your food and your baking pan.
But you are not putting just cardboard and pizza into the oven.
What else is in the cardboard pizza box?
Is there a sheet under the pizza in the box?
It might be waxed paper or parchment. Wax paper ignites around 400*F and can only be used in the oven if completely covered – like with cake batter – so it’s not exposed to the oven’s heat. Parchment is a little better; it is rated for 420*F to 450*F.
Maybe there isn’t a liner. Or maybe you remove that liner from the inside of the box to let the pizza sit directly on the cardboard.
Are you sure I can’t put the pizza box in the oven?
If the fire risk is not enough of a good reason, consider what you are heating along with your pizza.
That box has inks, dyes and laminates. Some boxes have adhesives. Most pizza boxes are made with recycled cardboard which retains the same contaminants used in making it for its previous use.
And what about that anti-grease layer in the cardboard that prevents the box from collapsing with the hot pizza? Like popcorn bags, cardboard pizza boxes can have phthalates and PFAS, those forever chemicals which create a resistance to heat, oil and grease. Avoid those toxic chemicals when you can.
While these extra additives won’t necessarily all burn at oven temperatures, they can be affected by heat and leach into your food.
You probably are not thinking about all those extra things. It is not just a piece of cardboard folded around your supper.
Assumptions and distractions happen!
It is easy to think higher temperatures will heat the food faster so you can sate your hunger sooner.
And it is easy to get distracted – your phone, your kids, your spouse, your pets – and leave something in the oven a little longer than you planned.
Plus you think you know how long it will take to reheat that pizza, but the closed lid on that box means you are just guessing. Every time you open the oven, heat escapes and the temperature drops. How many times do you need to check to make sure it is not overcooked? Not all pizzas reheat the same.
And the pizza is steaming under that closed lid. Holes in the sides of the cardboard pizza box may let out some steam, but there is a sauna in that oven. That can make your previously crispy crust into a soggy one.
Save the open flame for your pizza on the barbeque. (Fun side note: If you put pizza on the grill, use indirect heat instead of direct heat. So good!)
But My Frozen Pizza is On a Cardboard Base Already
That cardboard circle under your frozen pizza is a structural element designed to get your pizza from the factory to your kitchen. It is more cost-effective than plastic and ensures your pizza gets to your kitchen in one piece. Think of it as more packaging to be disposed of along with the plastic packaging. It is not bakeware.
The chemicals are here too!
The manufacturer usually coats the cardboard in wax, sealants or other chemicals to prevent condensation in case it defrosts at all in transit. Your partially defrosted pizza crust could absorb those chemicals. That leaching is likely responsible for that well-known cardboard pizza taste.
(If your pizza is stuck to the cardboard when you unwrap it, that is a good sign it has not remained frozen the whole time.)
Heating those chemicals fills your oven with toxic fumes. Your food can absorb them. Then you open the door, welcome them into the rest of your kitchen and you breathe them in.
The cardboard affects the reheating time
Besides, that little disc of cardboard is an extra layer between the heat source and the food which slows down the cooking time. Corrugated cardboard traps the heat which makes it a good insulator for the takeout pizza box, but not for reheating in the oven or anywhere else! You will have to wait longer to eat.
You want your frozen pizza on a metal pizza pan, baking sheet or pizza stone that conducts heat evenly to heat your pizza through and to crisp up that crust.
Cardboard pizza trays are no better to cook pizza. There are much safer options that are not a potential fire hazard. The cooking instructions for these frozen offerings can be as high as 425*F which does not leave much of a buffer between smoking and fire.
(Some frozen meals may come in a paper tray designed to be heat-proof and able to withstand oven temperatures. Read the instructions on the packaging and ensure all plastic is removed before you put it in the oven. The recommended oven temperature is often much lower than that for frozen pizza.)
The box for your frozen pizza is made with plastic-coated paperboard. This thin layer of plastic prevents freezer burn, moisture leaks and loss of food quality. It is not oven-safe either.
Start with Storing Leftovers Properly
A lot of people like to eat their leftover pizza cold.
If you absolutely want it hot, there are lots of great options to make it delicious pizza on day two. That starts with storing it properly so it is good for day 2.
At room temperature, leftover pizza still retains its crunch, but due to food-borne bacteria, you should not leave pizza out for more than 2 hours. Whether it’s vegan or covered in meat, the risks of gastrointestinal issues increase the longer it sits outside the fridge or freezer. Reheating may kill off some, but not all of that bacteria, but it will not get rid of the toxins from that bacteria.
Enjoy the convenience of the store-bought pizza. It’s a good idea to pack your leftovers into an air-tight container for the fridge or freezer when you finish eating and toss the whole box with its greasy, paper liner into the recycling or organic composting bin. Storing the leftovers in the cardboard box allows your pizza to dry out too much anyway.
What Are the Best Options to Heat or Reheat?
Try some alternative methods for reheating until you find the one that makes your food taste closer to delivery pizza. (Adding some fresh cheese or extra vegetables can help as well.)
Oven
The gold standard that nearly everyone has in their home.
1. Pizza Stone.
For frequent pizza connoisseurs, a ceramic pizza stone is going to be your best option. Preheat the oven to high heat (450*F or 475*F) with the pizza stone inside on the middle rack. Slide the pizza onto the hot stone. The hot stone will quickly evaporate moisture in the crust and prevent soggy bottom pizza while heating the pizza through.
This is where that cardboard circle from frozen pizza is handy; use it like a spatula to slide the pizza onto the stone in the oven. This oven is too hot for parchment paper.
If you do not preheat the stone, your pizza dough may stick. This can happen with frozen pizza as well.
2. A cookie sheet, baking sheet or pizza pan.
Spread your pizza slices on the pan with space between the pieces. With this method, 375*F should be sufficient. If you want a softer, chewier crust, opt for a lower temperature or a cold pan. If you want a crispier crust, you can put the baking sheet into the oven to get hot before adding the cold pizza to it.
Always use the middle rack to ensure even heat.
3. A sheet of aluminum foil.
This is the dish-free option. Place your pizza in the center, fold the two edges together and roll to create a sealed tent with space for steam to melt the cheese and prevent cheese from sticking to the packet. Place seam side up on the oven rack to avoid a mess of cheese and grease dripping to the bottom of the oven.
4. A glass casserole dish or baking dish.
Use what you already have if pizza is not a common meal in your dining rotation. There is no point in having one pan that you only use for rare occasions.
5. The oven rack.
You can set the pizza directly on the wire oven rack to maximize the crispy crust. This works better with a rigid pizza like the frozen kind than leftover pizza that was delivered last night. You risk the pizza falling between the wires or cheese dripping off the side. If you hate cleaning your oven, this is not a better way.
If you have the type of oven with convection bake mode, use this option to circulate the air for more even heating.
You will get your best results for deep dish and other thick crust pizza by setting a lower temperature and giving it a little more time.
Your baking time may vary. Kitchen appliances can vary on temperature so keep an eye on it. Trust your sense of smell.
Stovetop
A cast iron pan is a great option. Add your pizza slices to the cold pan, heat on medium heat for five minutes and check the crust. If you have a crispier crust than when you started, add a bit of water to the pan and cover to let the steam melt the cheese.
If you do not have cast iron, a regular skillet or non-stick pan at medium heat will work.
Microwave
When reheating in the microwave, add a mug of water next to your plate. The water will absorb some of the microwaves and let the pizza heat more slowly and evenly. It also prevents the edges of the crust from hardening as it cools. Use 50% of the power you normally would and try 30 second intervals.
Air Fryer
This method works better with a thin crust pizza than a thicker one. You can have crispy crust and soft cheese in 2-4 minutes at 350*F. The only drawback is that you can only usually reheat one slice at a time.
This is also the best way to reheat that cardboard box of chicken nuggets; it will likely take 4-6 minutes at 350*F, shaking the basket halfway, to get crispy but not soggy. Do not overcrowd.
Toaster Oven
It will only take three or four minutes at 350* depending on the thickness of your crust.
Be Safe and Enjoy Your Pizza
However you choose to reheat that pizza, the best and safest option is to keep the cardboard away from the oven. Yes, maybe you have put cardboard in the oven before without a problem, but it does not mean you will be so lucky the next time. Humidity, heat and the cardboard composition all have a role when you put that pizza box in the oven.
Take the extra time to transfer your pizza to an oven-safe pan or a safer alternative.
Additional Resources
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