A woman putting glass in the microwave

Is Microwaving Glass Safe to Do? The Best Types of Glass to Use and Avoid for the Microwave

I’m sure you have heard a lot of conflicting opinions about the safety of microwaving glass. Some people say it’s safe, while others say it is not safe at all.

What do you think? 

Honestly, I’ve been microwaving glass for years and have never had any problems – but maybe I’ve just gotten lucky…

So, is microwaving glass safe to do? Well, it’s not really a straightforward answer. It really depends on the type of glass!

In this blog post, I’ll be going over the different types of glass you can safely microwave and the glass you should avoid microwaving at all costs. Then I’ll share some of the glass products I use regularly and have had no issues!

What does microwave safe means?

You might be surprised to know that some glassware is safer than others in the microwave. When thinking about whether microwaving glass is safe to do, let’s define what it is.

Microwave safe products ensure the material of a container will not break or bend, release harmful chemicals and avoid any damage caused by extreme temperatures found inside most microwaves, it’s more than just aesthetics at play here!

Proper use can prevent foodborne illness too so make sure you only use cookware specifically labeled as “safe” when using this appliance!

Safe glass to microwave

Here’s my top picks for safe glass to microwave and WHY!

Borosilicate glass

Borosilicate glass is made from a combination of boron, silicon and oxygen. It is the most durable glass available for use in microwaves. Borosilicate glass dishes are dishwasher-safe and won’t shatter if dropped or left out in the sun too long. You can microwave these dishes and eat straight out of them.

What makes Borosilicate glass a safe choice to microwave is its high heat resistance and ability to handle temperature changes. It’s durability also makes it great choice!

Typically used in laboratories, this borosilicate glass has made its way into the kitchen over the past several years. Its best used as baking dishes, measuring glasses and glass cooking pots!

One thing to keep in mind, though – don’t use a Borosilicate glass bowl with metal utensils! It will scratch the surface over time.

Click to check out these top picks on Amazon!

Pyroceram glass

Pyroceram glass is a tempered glass that is resistant to breakage due to thermal shock. It is popular for use in microwave ovens because it doesn’t shatter like other types of glass when heated. It is actually the original glassware used in kitchens and the most popular!

However, Pyroceram glass dishes are not as durable as borosilicate glass and can be more at risk to breakage. While it is dishwasher-safe (though must be placed on the top rack) and oven safe up to 350°F/177°C, you may have problems if microwaved too long or dropped from a high height because of its increased likelihood of breaking in these cases.

So, while Pyroceram dishes might work better for those who want a cheap microwaveable set that will last awhile before having an issue with being broken due to thermal shock – I personally recommend Borosilicate glasses over these!

Corning Ware is the most popular brand for pyroceram glass and have may excellent choices when it comes to baking ware!

Check Out Pyroceram Glass


Pyrex is actually a brand, not a type of glass. Originally created in the 1950s using borosilicate glass, since the late 1990s, Pyrex uses a soda lime glass.

Pyrex glass is perfect for microwave use! However, here are some tips and tricks to get the most out of your dish.

  • Never pour hot liquid into a cold Pyrex dish
  • Pyrex is sturdy and thick, making it very durable
  • Pyrex is best used when using one device at a time For example, don’t put a Pyrex dish out of the freezer directly into the microwave. It will shatter.
  • Pyrex is suitable for extreme temperatures. It can withstand temperatures as low as -192 degrees F to 500 degrees F
Check Out Pyrex Glass

Unsafe glass to microwave

Colored glass

Microwaving glass is a common cooking technique. However, microwaving colored glass can be dangerous and should not be done.

Microwave ovens work by using radio waves to heat up food without drying it out or burning it. The waves penetrate the food from all sides at once, which cooks it quickly and evenly because the microwaves bounce around inside of the food as they cook it.

Colored glass often contains dyes and chemicals that can contaminate food, especially when heated. This can cause health concerns.

Also, when heating colored glass in the microwave, air bubbles can form and eventually expand and crack.

Glass with a Metal Trimming

When microwaving, the metal can cause sparks and a fire. Metals conduct electricity extremely well. The electrons on the surface of the metal move rapidly from side to side. The heat is never fully absorbed into the metal, causing a reflection aka the spark we see. This can cause issues with the microwave itself.

Ceramic Glass

While ceramic glass is actually safe for microwave use, it is not recommended. Here are some of the reasons:

  • Can crack and break easily if exposed to high heat
  • Do not microwave ceramic glass with painted designs on it. The paint typically contains substances that will cause sparks
  • Do not use ceramic that has a metal lining
  • When in doubt, look at the bottom to see if there is a “microwave safe” label

Is Microwaving Glass Safe to Do? – How to Test

When in doubt, you can always do a test to see if glass is safe to microwave. it’s super simple.

  • Step 1. Find the glass you want to test, whether it be a cup or small baking dish. Also find an approved microwave safe piece of glass.
  • Step 2. Fill the microwave safe piece of glass with water.
  • Step 3. Place both containers in the microwave on high heat for about a minute.
  • Step 4. Be careful taking the glass products out of the microwave. Now gently touch the glass you are testing to be microwave safe.
    • If the glass with water is hot, and the glass being tested is hot, it’s not microwave safe
    • If the glass with water is hot, and the glass being tested is not hot, it is microwave safe

Frequently Asked Questions

How Long Can I Microwave Glass?

It depends on the capacity of the glass container. It’s safe to microwave glass that contains 3 to 4 liters for 3 minutes. Anything above 4 liters, you can safely microwave for up to 5 minutes at a time. Once complete, rotate the dish and check to make sure the outside of the glass is not too hot!

What is Not Microwave Safe at all?

There are many dishes you should never ut in the microwave!

  • Aluminum
  • Metal
  • China
  • Stainless Steel
  • Paper Bags
  • Styrofoam

I hope this post has proved useful and now you know what glass is safe to microwave! If not, let me know how I can make it better in the comments!

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