What is the Microwave Safe Symbol – What to Know

The microwave definitely makes things faster and easier when it comes to cooking and reheating food. However, you’re not just going to throw a handful of spaghetti in there and make a huge mess. You’ll want to put your food on a plate or in a dish. But, what is the microwave safe symbol so you know what can and can’t go in the microwave?

Universally, the most common microwave safe symbol is 3-4 horizontal wavy lines. You’ll typically find this printed in a raised format on the bottom of your glass or plastic dish. However, there are some variations of this symbol and some good things to know about various materials. So, let’s talk about them more in depth!

what is the microwave safe symbol - what to know featured image

What Does the Microwave Safe Symbol Look Like?

The microwave safe symbol typically looks like 3-4 horizontal wavy lines, though can vary up to as many as six. Sometimes they are alone, but may also be accompanied by:

  • A rectangular box around them
  • Plate-shaped design underneath
  • Microwave-looking box with controls on the side
  • Bowl-shaped object under it
  • The word “micro” or “microwave”

In addition, we’ve seen some more less-common alternative microwave safe symbol designs such as:

  • A countertop microwave with vertical wavy lines over a plate
  • 4-6 circles gradually increasing in size within a square box bearing a 3-dot control panel at the top
  • Print only reading “microwave safe”

If you see any of the above symbols with an ‘X’ or a strikethrough slash “\” over them, this actually indicates that the dish is not microwave safe. 

What is the Microwave Safe Symbol on Tupperware?

Tupperware generally uses 3 horizontal wavy lines inside a rectangular box for their microwave safe symbol. You’ll find it on the bottom of their containers.

They also typically use a ‘/’ through the same icon to represent something that is not microwave safe.

Are All Tupperware Containers Microwave Safe?

No, not all Tupperware containers are microwave safe. In fact, many are designed solely for storage but not for the reheating process.

Make sure to check your specific piece of Tupperware for the presence of the microwave safe symbol. If it’s not there, even if a strikethrough isn’t there either, it still is not microwave safe. 

However, they make certain containers and cooking gadgets that definitely are safe. Learn more about a microwave pressure cooker and how handy it is!

is all tupperware microwave safe

Is Pyrex Microwave Safe?

Most Pyrex containers are microwave safe, including the plastic lids.

Make sure to double check your container for the presence of the microwave safe symbol just to be certain.

I often like to use these lids to cover food in the microwave because it’s very convenient!

How Do You Know if a Mug is Microwave Safe?

A mug is generally microwave safe, unless it:

  • Has any metal, whether the housing or a decorative rim
  • Contains non-microwave safe insulation
  • Is made from unsafe plastics

Metal should be pretty obvious to spot, but the others may be more tricky. Make sure to check the bottom of the mug for a microwave safe symbol. Read the included instructions or safety guide if you have one.

If there is no symbol present and no other factors that indicate the mug is not microwave safe, you’ll need to test it to confirm:

  1. Place the empty mug in your microwave
  2. Add a cup or bowl of water in a microwave safe dish next to it
  3. Set the microwave for 30 seconds of cook time on high
  4. Remove the mug and feel it with your hands
  5. If you feel heat in the mug, then it is not microwave safe

Are All Ceramic Mugs Microwave Safe?

All ceramic mugs should be safe to use in the microwave, unless they have been glazed with something non-microwave safe. This would generally be a glaze containing metal of some form.

Note that any mugs that have been repaired should not be used in the microwave, as most glues are not microwave safe. This will cause your mug to fall (back) apart.

are all ceramic mugs microwave safe

Are Paper Plates Microwave Safe?

Most paper plates are microwave safe. Some varieties that are not microwave safe are those that:

  • Have foil (metal) in the design
  • Are coated in a thin layer of plastic for waterproofing

Make sure to look at the exterior packaging of your paper plates for the microwave safe symbol, as it generally will not be printed on individual plates. If the symbol is not there, then assume that your paper plates are not microwave safe.

In fact, paper plates have to be the most common dish type used for microwaving pizza rolls!

Is Polypropylene (PP5) Microwave Safe?

Yes, polypropylene or PP5 is a microwave safe plastic. It is highly heat resistant and doesn’t absorb energy, making it perfect for microwave use.

Look for the recycling symbol with a ‘5’ in the middle, sometimes accompanied by “PP” underneath to know if you have a polypropylene container. 

Can You Microwave Styrofoam?

While you can technically microwave styrofoam, you shouldn’t. In most cases you won’t cause it to melt, but it will release non food safe chemicals when heated.

Styrofoam is made from polystyrene and is often chosen for its lightweight, sturdy, and inexpensive qualities for takeout.  It actually holds up without melting to around 200 degrees Fahrenheit, which would make it acceptable for microwave (but not oven) use.

However, polystyrene is known to release toxic fumes and non-food safe acids when heated. Thus, you should not microwave your styrofoam containers. Transfer the food to a safer vessel before heating.


Knowing the various microwave safe symbols will help you more easily identify proper dishes for your cooking or reheating needs. If you run into something that truly stumps you, test it out just to be safe.

Remember to always use caution with any dish in the microwave, as overheating and improper use can lead to damage – even of microwave safe containers. Follow your manufacturer guidelines and recipes to ensure you’re safely getting the best your microwave has to offer!

Katie Vine