Can You Put Cardboard in the Oven? Here's What Experts Say

Even if you have a dishware collection that could rival Martha's, you might have once been tempted: You open the oven, take a glance at last night’s leftovers still sitting in their cardboard box, and think—do I really need to dirty another dish? As convenient and harmless as putting cardboard in the oven may seem, it's worth a pause. At best it could burn your pizza; and at worst, it could be a potential fire hazard. 

To get clarity on what’s oven-safe and what’s better left to the trash or recycling bin, we spoke with fire safety and appliance experts. Here’s why cardboard isn’t the best choice for reheating your leftovers.

Let’s say an important cardboard shipping box got left in the rain, and you are desperate to dry it out. Or, you have a DIY project that involves heating materials. Or maybe, there's a pizza delivery that needs to remain warm while it's being picked over. Whatever the situation, cardboard and the oven do not mix.

While it may seem like a fine substitute for a baking sheet in many cases, cardboard is still paper—and paper burns.  

The Risks of Putting Cardboard in the Oven

"You cannot put cardboard in an oven," cautions fire safety expert Steve Lockwood. "Cardboard may catch fire at temperatures above 400 degrees," but even when the oven is set at a lower temperature (or is off), there is always risk.

Lockwood urges against using your oven as a storage space too, as accidents may occur. “Even if you don’t use the oven in your home, that doesn’t mean somehow, someway the knobs or the buttons on your stove won’t get accidentally turned on,” he says. According to Lockwood, storing anything in your oven is a guaranteed fire risk. "It’s not a matter of if it will happen; it is just when it will happen," he says.

Oven-Safe Alternatives

When cooking or thawing anything in the oven, only an oven-safe dish, pan, Dutch oven, or baking sheet will do. Per the directions on any commercially sold frozen pizza box, a pizza can either be placed on a baking sheet or pizza stone, or laid directly on the oven rack to cook to perfection. “Use a cookie sheet, jelly roll pan, or a pizza stone to cook with,” suggests appliance specialist Glenn Lewis. "Never anything flammable."

If you are hoping to keep a pizza delivery box warm, transfer the pizza to a baking sheet and keep it in the oven on a low temperature until it’s time to dine. Placing the cardboard box directly in the oven is not recommended. 

For DIY Projects and Crafts:

For any kind of craft project that involves exposure to heat, parchment paper placed on a baking sheet might suit your needs while meeting all of the safety precautions. Of course, be sure to follow all official instructions on the materials you're working with, paying close attention to temperature limits.