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Can You Microwave Cardboard?

In this article, learn which types of cardboard can be microwaved, which types can’t, and how to tell the difference.

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This post contains affiliate links. Please read my disclosure policy to learn more.

Is cardboard microwaveable? In this article, if learn which types of cardboard can be microwaved, which types can’t, and how to tell the difference.

If you’re like most people these days, you are looking to get more done, in less time, and with less effort. Right?

But can you pop your takeout cardboard box directly in the microwave? The answer is maybe but I choose not to. Here’s what you need to know.

microwave cardboard

Can You Microwave Cardboard?

Yes, you can microwave cardboard if it is labeled, “microwave-safe”. Otherwise, avoid putting cardboard in the microwave.

Can You Microwave Cardboard Boxes?

From time to time you may want to microwave cardboard containers. If you put cardboard containers in the microwave, please make sure they are marked, “microwave safe” and that you do not microwave for too long.

From my research, if a cardboard container is marked, “microwave safe, ” it should be safe to microwave on a lower setting for a short period of time.

How short of time and at precisely what setting?

It all depends on your microwave and in my research, I couldn’t find any concrete guidelines for you.

I suspect the lack of concrete guidelines is a liability issue due to the varying powers of microwaves.

Unfortunately, most cardboard containers don’t say anything about whether the cardboard is microwaveable or not. 

So, if you still insist on microwaving that cardboard, you must do the following each and every time you microwave cardboard containers:

  • Look for and remove all metal. Make sure there is no metal on or in the cardboard container like metal handles as they may spark and cause damage to your microwave.
  • Make sure the cardboard container does not contain plastic or wax coatings that could melt or emit toxic fumes.
  • Ensure there is food in the container so the cardboard doesn’t catch on fire. Because microwaving cardboard by itself is a safety hazard, I thought I would mention it.

How Do You Know If Your Cardboard Contains Metal?

Some cardboard containers have metal handles so they would need to be removed. You should inspect the outside of the package carefully.

As to whether your cardboard contains any small metal fragments from the manufacturing or recycling process, there is no way to be 100% sure. When in doubt, don’t microwave the cardboard.

How Can You Tell If Your Cardboard Has A Plastic Or Wax Coating?

Many containers like milk may have a plastic coating on the inside to keep the liquid from seeping through the cardboard. 

Cardboard that is coated in plastic or wax is smooth and slick. Not sure if there is a wax coating? Try scraping your fingernail across the container to see if you scrape off any plastic or wax.

How Long Can You Microwave Cardboard?

Reheating food for too long could damage the cardboard container rendering your food inedible. 

Just how long is too long? Honestly, I don’t know. I spent a long time trying to find out that answer and I don’t believe it exists. The reason is probably due to the fact that microwaves vary in power. 

Does Reheating Food In Cardboard Containers Save Time?

In my experience, no!

It takes me more time to carefully inspect a cardboard container then it does for me to pop the food on a microwave-safe plate and wash the plate after I was done.

Is Reheating Food In Cardboard Containers Worth The Risk?

In my humble opinion, absolutely not!

Don’t take a chance of exposing your family to potentially harmful toxins or risk a fire or other damage to your microwave over a cardboard container!

Err on the side of caution. Get your family in the habit of never heating food in cardboard containers.

Can You Microwave Take-Out Boxes?

Most cardboard take-out boxes are designed to be one-time use boxes are likely not microwaveable. These boxes may contain pieces of metal or have a wax coating.

Before microwaving any cardboard take-out boxes, look to see if they are marked microwave safe.

Can You Put Pizza Boxes In The Microwave?

Again, as with other cardboard pizza boxes, most take-out pizza boxes are made to be used once. Most pizza boxes are not microwaveable.

It’s best to avoid reheating pizza in its take-out box.

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Final Thoughts From Cost-Effective Kitchen

The only way to know with a fair amount of certainty that your cardboard container is microwavable is for your cardboard box to state it is “Microwave Safe.”

Otherwise, you could be playing with fire…literally! 

And you could be exposing your family to harmful toxins!

Most cardboard containers won’t state they are microwave safe, so you will need need to take the time to carefully check every container for metal and plastic or wax coatings before you put it in the microwave. 

You will also need to be careful not to microwave it for too long or too high of a setting. 

Furthermore, if your kids reheat items in the microwave, do you trust them to remember which cardboard is “microwave safe” and which is not?

My recommendation is to never microwave any cardboard in the microwave. It is just not worth the risk or effort!

It will take you less time to grab a plate or bowl from the cabinet and to wash that plate than it will to properly inspect a cardboard box.

I always err on the side of caution when it comes to my family’s health and well-being.

However, if you really want to reheat food on a microwave-safe plate, try these!

Until next time…


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