Can you Microwave Mason Jars? Answers You Must See

I know how it feels to be so famished and not have time to think about anything else. 

When your food is stored in a mason jar and you are sprinting towards the microwave, the last thing you think is safety first. Instead, what consumes your mind is “if I don’t satisfy this growling monster ASAP, it’s going to eat up my belly!”

In that state of mind, if you have spared (even) a split second to think about the safety of your action, it can be frustrating to not immediately have the answers.

Now that you are doing the right thing, consulting your internet best pal and know-it-all (quirky me!) I have taken it upon myself to help. 

This article is a comprehensive but simple guide. It will help you know everything in the middle of the microwave and mason jar Venn diagram.


Yes, a certain group of mason jars can be microwaved. These jars come with a microwave-safe label. So, if you are holding one that has no label, it is most likely an old model that was not carefully made to resist heat. Therefore, it poses a great danger if microwaved.

If your Mason jar has a microwave-safe label, good for you. You can microwave it. If not, find another container – a microwavable one – and use that instead. If not, you could be playing with danger.

What are the risks and dangers of microwaving mason jars?

This is a good question, especially because glassware is popularly regarded as microwave safe. But contrary to public opinion, not all glassware can withstand the heat from a microwave. Some Mason jars are in this category. They are not compatible with microwaves and there is a danger in ignoring the risks.

A potential hazard may occur by leaving the screw top and lid of the Mason jar on when microwaving. Even if the Mason jar is microwavable, you should never do this.

A standard Mason jar is made with annealed glass. This is not tempered glass, so it cannot withstand high heat. It can sometimes withstand heat and cold, though not for too long.

 A big contrast, which I find weird between annealed glass and tempered glass is that even when the former breaks, it breaks into tiny pieces with less potential to hurt. Meanwhile, when annealed glass breaks, it breaks into big, jagged shapes that can injure you.

The funny thing is that despite their tendency to shatter under the pressure of high heat, they are stronger than you think. They are good for all other uses, except microwaving on high heat and for too long.

Though microwaving Mason jars is not recommended, in a few minutes, I will share what steps you can take to be safe when microwaving a mason jar.

But then, why are Mason Jars so insanely popular?

The Mason jar is increasingly replacing the coffee mug. All my coffee lovers, holla! The jars are pleasing to the eye, cheap, portable and convenient. 

It was initially meant to be a canning jar, now it is so much more. It is so versatile as it can be used to store any and everything you can think of, even decorations.

It is so durable. If you handle it with care, you can use it for years. This is both a good thing and a bad thing, as most Mason jars that are not microwavable are the old ones. Apart from the age, other factors determine whether you can microwave a Mason jar.

Another critical element to consider is whether there is a label at the bottom of the jar symbolizing that it is microwave-safe or microwavable.

Since it has been established that Mason Jars cannot withstand high heat, another question comes up.

Can you pour boiling water into a Mason jar?

Mason jars will not be affected by boiling water, nor will anything happen even if they are dumped into a bowl of boiling water for sterilization. The only thing you must not do is take a frozen Mason jar and put it into boiling water. If you do, you will destroy it.  

Ever heard of thermal shock? When glass moves from one extreme temperature to another, it breaks. A frozen Mason jar simply cannot tolerate boiling water. So, whenever you want to sterilize it, put it in lukewarm water and allow it to come to a boil along with the water.

Is it safe to microwave frozen food in a Mason jar?

It is the same thing. You can’t microwave frozen food in a Mason jar. It’s not just me. The experts have said so. You can be safe by placing the jar in a bowl of water and letting the food inside defrost. 

If the jar is still cold after defrosting its contents, it is better to get the food out of the jar and into a microwave-safe plate for microwaving. 

If you must microwave the jar, make sure you don’t cover it, you put it inside a bowl of water and microwave on defrost for 20 seconds at a time.


Mason jars with microwave-safe labels are safe to microwave. They are less likely to withstand high heat for too long, so be sure to use them only for items that heat up fast and are good to go after a few minutes.

If you microwave a Mason jar, you cannot put its metal lid on, while it is heating. Metal is a menace when allowed to go in a microwave. In the same way, you must keep old and cold Mason jars away from the microwave.

If you’re not 100% certain that the jar you are about to heat up is microwavable, DON’T DO IT.

Even where the Mason jar is microwave-safe, you still have to be careful. Every form of glass can absorb heat. So, don’t go touching it. Use oven mitts, gloves or a towel to take out the jar from the microwave.

One more thing about the metal lids. They’re not only bad for the microwave, but they can also be corrosive. This single characteristic can spoil the quality of your food and make it difficult to open the jar. What I advise is that you get plastic lids in their place because those metal lids are trouble!

If you follow all these precautions carefully, I still must mention that using a microwave-safe Mason jar is key to safety

How do you know a mason Jar is microwave safe?

The best and most safe way to tell that your Mason jar is microwave-safe is if it comes with a label at the bottom or anywhere on the body stating that it is safe to use in a microwave. 

If your jar does not have a label, yet for some reason, you sense that it might be microwavable. Or if it has a label and you just want to do a double-check. Here’s a super quick and easy way to confirm. 

Place the jar in the microwave. Make sure it is empty, with no food or drink inside. Microwave it for about a minute or two. Take out the jar and inspect it for cracks or anything weird. But this test only applies to thicker glassware. Thin glass jars are too fragile to withstand heat and are, therefore, not eligible for this test.


No matter what you’re doing or how big your Mason jar is, you can’t afford to leave your Mason jar in the microwave for more than 5 minutes.

For a 1-liter jar, you can’t even let it stay in the microwave for more than 2 minutes. A 2 to 4-liter jar will break if it is microwaved for more than 4 minutes. 

Your best bet is to microwave in short intervals of 30 seconds so that the heating does not overwhelm you or the jar.


If you want to microwave your Mason jars safely and efficiently, you will do well to follow these tips.

  1. Make sure your Mason jar has no cracks or chipped parts before going into the microwave.
  2. Hygiene is paramount. Take care to clean your jar before use.
  3. Under no circumstance must you put a lid on a jar that will be microwaved.
  4. Avoid subjecting your Mason jar to extreme changes in temperature.
  5. Don’t microwave an old or thin-glass Mason jar. It might stretch and break under the pressure of heat
  6. When reaching into the microwave to take out your jar, protect your hands with oven gloves or a towel.
  7. Heat slowly and in short intervals. Also, remember to stir the content during each interval to avoid uneven heating.


Mason jars are the crème de la crème of jars lately. So, it makes sense to use it for any and everything. They are super convenient and versatile. We all love them. But we must be super careful when using them in the microwave for the sake of our safety. 

In this article, I have discussed extensively whether you can microwave a mason jar, whether it is safe, how to do it, and for how long. So, I consider you pretty armed and prepared for the task ahead.

Always remember, if you’re not 100% certain that a Mason jar is microwave safe, take the test I taught you here or abstain or use the other safe methods I shared with you.