Can you Microwave Cold Pyrex? 9 Tips to Keep In Mind

Not having any Pyrex containers with which I can store my leftover food is the bane of my existence. They are so convenient for use in the microwave and the refrigerator. I simply CAN NOT live without them. 

I’m sure you feel the same way too. Everyone feels that way.

But then things can become tricky when you want to microwave your food in a Pyrex container that has been sitting in the freezer for hours. 

You wonder if it’s safe, if there is a right way, what the dangers and risks are and what tips and tricks could help you carry out the task smoothly.

In this article, you’ll get your answers to everything.


It is not advised to microwave cold Pyrex glassware. I know the manufacturers say it is microwave-safe and refrigerator safe, but hear me out. Pyrex glass containers cannot cope when subjected to an extreme change in temperature. They just… fall apart. So, if you try to switch from cold to hot in seconds, they shatter or at least crack.

The manufacturers of Pyrex say that it can be used in microwaves, ovens, and refrigerators. But many people have complained, reporting either cracking or shattering as their experience when they tried to microwave cold Pyrex.

If I were to address the elephant in the room, I would say that the manufacturers are not entirely to blame. They didn’t lie, they just failed to communicate that the product is susceptible to thermal shock. That a sudden temperature change, whether from hot to cold or cold to hot is dangerous and can cause Pyrex glassware to crack or shatter.

Pyrex is no longer made with borosilicate glass, as you would like to think. Rather, it is made with tempered glass (soda-lime glass), which copes less with a sudden temperature change.

Why, though?

I do not have the answer to that. It may be because they wanted to cut the cost of production. I don’t know. But it is worthy of note that other manufacturers have done the same too. So, cut Pyrex some slack, please.

It’s not all bad. At least, the Pyrex of today (made of tempered glass) can cope with thermal shock better than regular glass. It’s just that it doesn’t stay together as much as it used to.

What’s the implication of this?

This means you can’t take cold Pyrex glassware from the freezer and immediately put it into the microwave or oven and vice versa. 

This means you can’t pour hot liquid into a cold Pyrex cup.

This means you can’t place a hot Pyrex container on icy cold surfaces.

This means you cannot microwave an empty Pyrex container, no matter what!

Do you understand?


If you must microwave a cold Pyrex product, be sure to take it out of the freezer and set it on the kitchen counter for 15 minutes or more. When the food is back to room temperature, you can microwave it. 

Don’t take Pyrex out of the freezer and put it straight into the microwave. Give it some time to prepare itself for the heat, so it doesn’t shatter or explode.

The scary thing about leaving food on the counter is the temperature danger zone. Bacteria tend to grow rapidly in food left in the range of temperatures between 40 degrees Fahrenheit and 140 degrees Fahrenheit.

As a result, most people are worried that their food could become contaminated if left to defrost. 

However, the USDA Temperature Danger Zone Guidelines assure us that as long as the food is cooked or refrigerated within 2 hours, it is safe to consume. So, you can leave your food on the countertop for about 15 minutes to defrost. 

If you’re still not comfortable with this method, get a bowl of lukewarm water and leave your cold Pyrex in it for a few minutes. This works like magic to bring it to room temperature.  

You can avoid allowing the dish to heat up rapidly and risk thermal shock from an abrupt temperature change.

How do you prevent cold Pyrex glass from exploding in the microwave?

Apart from leaving your cold Pyrex on the counter, there are other tricks you can use. I’ll show you in a minute. But first, you must promise me that you’ll be careful to follow the manufacturer’s instructions. Deal?

Okay! Here goes;

  • Preheat the microwave

Since we’ve established that cold Pyrex can’t stand an extreme temperature change. How about you preheat the microwave at convection mode first and then switch it off, before putting the Pyrex into the microwave? Smart, right? The radiant heat will do most of the work for you and then you can proceed with your task.

  • Set a temperature limit

What about setting a temperature limit on your microwave? It’s tricky, so let me explain. You know that Pyrex glass can cope with high temperatures. It only collapses when it has to quickly go from extremely cold to extremely high. So, if you don’t exceed the recommended temperature of 350-425 degrees Fahrenheit, then you can prevent thermal shock from happening.

  • Start with a low temperature

When you start microwaving your cold Pyrex container, do it on low and then gradually increase the temperature. You have to be very careful and attentive though.

I use these methods myself and they work very well. The trick is to make sure that the temperature change is gradual. It’s kinda like wooing a lady. Try it and see. No, I don’t mean you should woo the lady, just the temperature change thingy.


It is risky and may not be safe to microwave cold Pyrex. If you do, you will have to be very careful. When you subject cold Pyrex to abrupt temperature change, it might crack, break or shatter. 

The thing is, Pyrex glassware is usually thicker and harder than other kitchen utensils made of glass. 

When you put it into the microwave and subject it to a sudden spike in temperature, the temperature of all the different elements will increase at different speed rates. This is what causes thermal shock, resulting in microwave explosions, cracking and shattering of the glassware.


Here are some tips for handling Pyrex glassware dishes.

  1. Pyrex glassware is not made for the stovetop or electric burner. You can only use it in the microwave.
  2. Trying to heat oil, butter, popcorn bags or grill meat in a Pyrex container can be dangerous. So, don’t do it.
  3. Make sure that your Pyrex does not have any cracks on it before putting it in the microwave.
  4. Some microwaves are greater than others in wattage. So, be sure to be conversant with your microwave and its power levels.
  5. Don’t put your bare hands into the microwave. It makes no sense if you don’t want to get burnt. Get some gloves on.
  6. When you are heating foods that require very high temperatures for long periods, stay away from Pyrex. Use an alternative microwavable container or use a stovetop instead.
  7. When taking out your glassware from the microwave, don’t put it directly on a cold surface. Remember what you’ve just learned about rapidly changing temperatures? That’s right.
  8. If you are cooking a dry dish in your Pyrex glassware, add a bit of water to the bottom of the Pyrex container so it does not get too hot.
  9. Don’t pour hot water into a Pyrex container. You’ll risk breaking or cracking it.


It is not advisable to microwave cold Pyrex. If you do, you have to carefully follow the steps, tips, and instructions given in this article.

Though the manufacturers assure that Pyrex is both microwave and refrigerator safe, the issue arises when there is a sudden temperature change. 

The manufacturing company has some guidelines on how the Pyrex should be used. Be sure to follow them carefully.