The best way to reheat pizza (and some things you should never do)

PopSci is spending September relearning how to eat. As intuitive as our love of chowing down is, a lot stands between us and optimal eating. This month, we’ll break down diet myths, unlock delicious kitchen hacks, and explore our most common misconceptions about our grub.

Order pizza, and there’s a good chance it’s gone within hours. Something about that round wheel of dough, melted cheese, warm tomato sauce, and seemingly countless topping possibilities is simply irresistible. If only pizza would stay that way forever.

Still, it’s hard to resist the temptation of a leftover slice as you rummage through the fridge for food the next day. Maybe you like cold pizza—there’s no shame in that—but if you’re looking learn how to reheat pizza in a way that restores some of that fresh-pizza magic, you’ll need to know what you’re doing.

So, Popular Science’s DIY team tracked down the most popular strategies, bought a whole lot of pizza, and put them to the test. We sought the ultimate method—The Way.

To truly understand pizza, you must know how it dies

The very moment pizza is born out of the oven, it’s too hot to eat and might not even be done cooking. But right around 140 degrees Fahrenheit—the temperature experts recommend you dig in so you don’t burn your mouth—it begins its inevitable march toward complete decay, just like everything else on Earth.

If you can’t (or won’t) eat your pizza when it’s fresh, all you’ll be able to do later is damage control. You see, cheese only likes to be melted once, because when it does, it loses its integrity. When exposed to high temperatures, cheese loses fat and water, and there’s just no way to get it back.

“That water isn’t going up,” says bread and pizza expert Francisco Migoya, head chef at Modernist Cuisine. “The dough is like a sponge, so it’s just going to absorb it all, making it soggier and gummier as time goes by.”

Over time, the moisture from the sauce and water, plus the fat from the cheese (and any meat), seeps into the crust, creating what pizza connoisseurs know as “the gum line”—that layer between the sauce and crust that looks like raw dough. The thicker the pizza, the more pronounced the gum line will be, and the longer it sits there uneaten, the thicker it will get. This, Migoya says, changes the crust permanently.

You should never leave pizza out on the counter or in the oven overnight (because of bacteria), but putting it in the fridge doesn’t do it any favors. Low temperatures congeal everything the dough has absorbed and accelerate the staling process, or retrogradation. In short: The starch in the crust recrystallizes, and all that fresh-pizza chewiness goes out the window.

How we did it

PopSci is based in New York City, so we tested each method with the thin-crust style of pizza the Big Apple is famous for. If you’re reheating Chicago-style deep-dish pizza or another variety, your results may vary.

Top tier 🍕🍕🍕

Reddit’s favorite

The official reheating method of the /r/pizza subreddit, this calls for placing your cold pizza on an oiled, preheated non-stick pan and cooking it for two minutes over medium-low heat (or until the bottom of the slice is crispy). Then, pour two drops of water (less than a teaspoon) into the pan as far from the pizza as you can get. Cover the pan with a lid and turn the heat to low. Cook it for another minute.

Using a cast-iron pan, however, amplifies a number of factors you may not want to deal with while heating up a quick bite. Depending on your stove, it may take what feels like forever to warm the thick metal pan. And if it’s not properly seasoned, tossing a cold slice onto hot, dry iron is a recipe for burned crust (more on that later). Even if you get the pan hot with a thin sheen of oil, the crust will become extremely crispy before the cheese has much of a chance to melt.

Hot tray in a hot oven

Put a baking tray in your oven and heat it to 500 degrees Fahrenheit. If you don’t want to clean the tray later, you can line it with foil. Once the oven has reached the proper temperature, use an oven mitt to take the hot tray out and put your slices on it. Place the tray on the middle rack and cook it for five minutes. If your oven runs hot or your ‘za is a little too crisp for your liking, cook it for the same amount of time at 450.

The results

We had to let the pizza sit for a minute or two to cool down before we could eat it, but when it passed between our lips, we experienced excellent crispiness, melty cheese, and a slice that was almost as good as new. For what it’s worth, one author considers this the best way to reheat pizza.

You can play around with different temperatures, but you should always make sure the tray heats up with the oven. We tried it at 375 degrees for 10 minutes, and while the first bite was crispy and tasted great, the slice became hard to chew the closer we got to the end—more like a cracker, less like a pizza. A cheese slice came out quite dehydrated, but a pepperoni one was fine—the fat in the meat likely helped keep the cheese moist. The crust on the pepperoni slice was better too: It was the right amount of crisp and wasn’t tough to chew as it got thicker.

Air fryer

If you want to reheat pizza in an air fryer, we’ve got you. Put a slice of pizza into a cold air fryer, turn the heat to 400 degrees and let it cook for five minutes. We put it directly on the air fryer tray, no foil, and it didn’t make too much of a mess. The drip tray caught any excess, too. This combination of heat and time worked best for us, but given the variety of available air fryers, you may find your sweet spot lies somewhere between 360 and 400 degrees, cooked for four to eight minutes.

The results

This is by far the fastest of the top-tier methods. You won’t have to wait for a pan or oven to heat up—just pop it in the air fryer and go. Five minutes later, you’ve got a crisp, bubbly, delicious slice. There are some downsides, though: you can really only heat one slice at a time, and more fragile ingredients (such as vegetables), may begin to burn after five minutes. At eight minutes, even at 360 degrees, the whole crust was burned. So don’t delay getting it out of the fryer and onto your plate.

Middle tier 🍕🍕

Straight-up rebaking

We did it anyway. For science (with a sheet of aluminum foil on the rack below to catch any drippings and hopefully prevent a fire). But you definitely shouldn’t.

The results

The best iteration of this strategy was baking the pizza on a sheet of foil (not directly on the rack) at 450 degrees for five minutes. The crust was crispy, the cheese was warm—solid all around, but not as good as rebaking it on a hot tray. You can also do it at 350 degrees for 10 minutes for a slightly less-crispy slice, if that’s your thing. Our worst results with this method came when we put the pizza directly on the oven rack. We didn’t start a fire (we had a fire extinguisher on hand), but the crust was unevenly cooked due to the lack of a solid heated surface underneath. Ultimately, this isn’t the best way to reheat pizza, but it’s not the worst, either.

The microwave + oven combo

We were pretty skeptical about this technique, but it surprised us. First, put the pizza in your microwave for 30 seconds. Then, put the pizza in a tray in a cold oven and set it to heat up to 350 degrees. Once the oven tells you it’s done preheating—when you’d normally put food in—take the pizza out.

Low and slow in the oven

The worst 🍕

A very hot pan

Cast-iron was worse. In a dry pan, the crust began smoking the moment it hit hot metal. The smell of disastrously burned bread hung heavy in the air for hours. Somehow, the pizza was still cold on top. If Hell ever freezes over and we get the chance to taste it, this is probably what it would be like: scalding, burnt, and covered by a layer of cold, congealed fat.

We oiled the cast-iron to give this strategy a second chance and it didn’t start to burn immediately—that took about three minutes. The crust was better (maybe too crispy), but the cheese was still lukewarm at best.

Microwaved with a mug of water

Simply put your pizza in the microwave with a microwave-safe mug of water and heat them both up for a minute.

Microwave disasters

1. Set your microwave to 30 or 40 percent power and heat the pizza for 45 seconds. Check it out and repeat as often as necessary.
2. Put a wet paper towel over your pizza and microwave it for 100 seconds.
3. Heat it upside down on a plate for 145 seconds (2.5 minutes).

[Related: I spent 13 hours trying to make mac and cheese in a bag. It was a disaster.]

The results

1. The crust was gummy—not crispy at all. The cheese melted but was highly dehydrated, so it didn’t have much taste and its consistency was rubbery at best. No matter the topping, they tasted as if they had been reheated in the microwave for two minutes. Total waste of delicious food.
2. Our paper towel was barely damp and it still soaked the pizza. The bottom was super wet, the whole thing was limp and floppy, and biting into the crust was like trying to eat an old shoe. Plus, we couldn’t pick up our slice for several minutes because it oozed steam and hot water at the lightest touch.
3. This method actually wasn’t bad for the cheese if you ignore the fact that a lot of it ended up stuck to the plate. But the crust? Just awful: leathery, rubbery, and we had to snap the thickest part like a twig.

This post has been updated. It was originally published on February 7, 2020.