Can You Microwave a Mason Jar? Safe or Unsafe?

Categorized as Microwave Safety
can you microwave mason jars

Mason jars are an excellent food storage solution. Home canners and gardeners have long relied on them for the safe storage of their goods. Just ask your grandmother or grandfather if they had been canning with Mason jars, and you will likely get a nostalgic response to the thought of these items.

One of the common questions that often come up among people who are new to Mason jars is whether or not they can put Mason jars in the microwave. Some people will say that you can, and others will mention that microwaving Mason jars should never be done.

Here’s the answer to that question.

Can You Microwave Mason Jars?

Yes, you can microwave Mason jars. The newer type of Mason jars is designed to withstand the heat of microwaves. You can verify this by looking at the bottom of your jars, where you will find a message similar to “microwave safe” or “microwaveable.”

However, keep in mind that although glass mason jars are non-reactive, it still becomes very hot to the touch when microwaved. So it’s best not to microwave food that requires long periods of time in the microwave.

A safe way to go about this would be to use Mason jars for heating food that only takes a few minutes to microwaves, such as pre-cooked pasta, soup, and cheese dips.

How To Tell If Your Mason Jar Is Microwave Safe or Not?

There are several factors that can determine whether or not a Mason jar is microwave safe. Here are a few of them:

1. The Jar’s Age

The first factor to consider is the age of your Mason jar. Older jars were made with a different type of material, and they were not safe to be microwaved. So if you have an older jar, it would be best to avoid microwaving it.

There are many ways to date the jars that you have. One of the most obvious ways is to look at the logo imprinted on the jar. Along with the logo, you can sometimes look at the color, size, and other distinguishing cues to help determine the age of your jar.

If you’re using a Mason jar made by Ball, then you can look at the following infographic to figure out the age of your jar:

2. Microwave Safe Symbol

Another equally critical factor to consider is whether there is a “Microwave Safe” symbol on the jar. This symbol can usually be found on the bottom of the Mason jar.

If you can’t find the symbol, you can look at the message imprinted on the jar or on its lid. Some jars will say, “Not for Microwave Use.” Another thing you can try is to visit the manufacturer’s website to see if the jar is listed as “microwave safe” or not.

Microwave Test To Determine If Your Mason Jar Is Safe To Use?

For those who are experimental or who want to be sure about using their Mason jars in microwaves, you can perform a small test on the jar.

To do this, fill the Mason jar with one cup of water and place it in the microwave. Set your microwave to its highest setting. Microwave the jar for one minute.

Remove the jar from the microwave and check to see if it’s hot. If the jar is hot, do not use it again in the microwave. If it is cool, you can heat your food, and you can be sure that you are using a microwavable jar. It is okay if the area around the water is warm, but the rest of the jar should be cool to the touch.

Be careful when removing the jar from the microwave and use oven mitts or potholders when taking it out to avoid the possibility of getting burned.

How Long Can You Microwave a Mason Jar?

The main reason most people microwave their Mason jars in the first place is to sterilize them. If this is your main goal, then the time it takes to microwave the jar will depend on its size.

Here’s a general guide on how long you can microwave a jar:

  • Small Mason jars less than 1-liter capacity: 1-2 minutes.
  • Medium Mason jars with 1-4 liters capacity: 3-4 minutes.
  • Large Mason jars over 3 liters capacity: 5 minutes.

To reheat quick-heat items, you would only need to microwave the jar for about 1 to 2 minutes.

Remember once again, make sure that the jar has a label that specifically states “microwave-safe” before microwaving the jar.

Here’s a short guide on how to sterilize a Mason jar in the microwave:

  1. First, wash the jar with baking soda or use warm, soapy water to remove any dirt or debris from the jar.
  2. Pour water into the jar and microwave it following the duration that I have just stated above.

Tips for Microwaving Mason Jars

Here are some more tips for microwaving Mason jars:

  • Remove all the metal components from the jar before microwaving, including the lid and screw top. Metal in the microwave is a definite no-no as it will cause an explosion in the microwave.
  • If the jar is tightly packed, it’s better to transfer the food to another container before microwaving.
  • Even if your Mason jar is safe to use in microwaves, it can still pick up heat and can be too hot to handle, so use oven mitts or potholders when removing it from the microwave.

Is It Safe To Microwave Frozen Food That’s in a Mason Jar?

It’s a common practice nowadays to defrost frozen food in the microwave. It’s quick and convenient. But what about microwaving frozen food that’s in a Mason jar?

You shouldn’t microwave frozen food that’s in a Mason jar because it can cause the jar to break. During the microwaving process, the jar temperature will increase rapidly.

When this happens, it can cause thermal shock, which is when the jar glass is exposed to sudden temperature changes beyond its tolerance levels. This can cause the structure of the jar to expand, and at certain limit points, it can cause the jar to fracture and break.

The safest solution to thaw frozen food stored in a Mason jar is to submerge the jar in a water bowl. Change the water every thirty minutes until the content of the jar is thawed, and then you can proceed to heat the food in the microwave.

What Other Ways Mason Jars Are Used?

Mason jars are not limited to storing food. You can also use it for other things like storing items or creating something impressive with them. For example, you can use old jar lids that are no longer used to create toothbrush holders, stained glass jars, welcome signs, and many more.


As you have read so far, it is safe to microwave Mason jars as long as the jar has a label that states “microwave-safe” on it. If you are microwaving a Mason jar, then certain safety precautions must be taken before doing this. Be sure to read the safety tips section to make sure that you are aware of the dos and don’ts.

By Rosie Elliott

I’m Rosie. I’m a professional chef with experience in Western, Mediterranean, and Italian cuisine. I’ve been cooking for over 15 years, and I have two daughters that keep me busy!