Can You Microwave a Starbucks Tumbler? 

I’ve had the experience a few times before- leaving my Starbucks tumbler out for too long until the coffee inside gets to a cooler temperature that’s not so enjoyable when drinking. Standing there I begin to wonder what would happen if I just quickly put my tumbler of coffee in the microwave oven to reheat it. 

Is it even ok if I just slip my Starbucks tumbler filled with coffee into the microwave for a few seconds? Will it do any harm? Based on extensive research I have found that it’s not good to microwave Starbucks tumblers.

Starbucks mainly uses stainless steel and plastic tumblers which come with warnings against microwaving. These tumblers should only be used to hold hot or cold beverages, and should not be placed in a microwave for reheating. 

Starbucks also uses reusable plastic, paper, and ceramic cups. Once there is a label that warns against microwaving then it is strongly advised that you follow these instructions. Sometimes there is no warning against microwaving but it is a general rule to avoid heating any form of plastic or metal in a microwave unless it is labeled as microwave-safe.

In this article, I will provide you with all you need to know about microwaving Starbucks tumblers and cups, as well as how you can quickly reheat your coffee in a microwave. 

How Is a Tumbler Different From a Cup?

In general, cups will come with a handle for holding while the coffee tumblers will not have any handles. 

Another distinct difference is the insulation that tumblers have. Some tumblers have a layer of vacuum-sealed inside to reduce heat loss, and others are lined with insulating materials. This feature allows your beverages to stay warm or cold for longer periods. 

Cups do not have this insulation feature and are generally there to simply hold hot or cold liquids for drinking immediately.

What are Starbucks Tumblers Made of?

Starbucks uses ice stainless steel, iridescent stainless steel, ceramic, acrylic, and recycled plastics for their different tumblers. They come in different sizes and designs. Each type of tumbler has a form of insulation that keeps liquids warm or cold for a time. 

There are two types of insulating tumblers:

  1. The first type is best suited for coffee and is made with double-walled stainless steel along with a slide tab, a seal-tight lid to prevent spilling, and a fastener. The double walls seal in a vacuum which prevents the heat from escaping too quickly into the environment. These tumblers can get quite hot when drinking hot coffee so you may need to use something to hold it until it cools.
  2. The second type does not have a vacuum seal but is made of various insulating materials. The Starbucks tumblers do not use this method since vacuum seals are more effective and keep your liquids warm or cold for longer. 

Which Starbucks Tumblers Can You Microwave? 

Aside from the ceramic tumblers, all other types of Starbucks tumblers should not be microwaved. If the ceramic is too thin, however, microwave on low heat and be careful not to burn your skin while drinking.

Stainless steel is a metal and therefore would not be safe for microwaving. If you attempt this you will find sparks flying around in the microwave until a fire starts. The plastics can also melt and destroy your tumbler.

In addition to that, Starbucks tumblers are lined with wax which can be toxic if melted into your beverages and consumed. 

Is it Safe to Microwave a Starbucks Tumbler?

It is only safe to microwave Starbucks tumblers that are not double-walled, and are not made of plastics or stainless steel. To be sure, check the bottom of your tumbler to see if it has a “microwave-friendly” label. If it does not, then it is best to use a different container. 

Based on my research, most Starbucks tumblers are not safe for heating in a microwave. 

Can You Place Hot Coffee Into Starbucks Tumblers?

Yes, you can. The purpose of tumblers is to hold hot or cold liquids and retain their temperature for a few hours. Therefore, it is safe for you to put beverages that have already been heated into your Starbucks tumbler, but you should never attempt to reheat the tumbler in a microwave.

You can safely pour hot liquid into your Starbucks tumbler without worrying about getting burnt. Thanks to the different types of insulation provided by these tumblers, they are perfect for you to grab and go when needed.  

What Happens If You Microwave Starbucks Ceramic Tumblers? 

If you microwave a beverage inside of a Starbucks ceramic mug then you may notice one of two things:

The first possibility is that the mug may be extremely hot while the liquid inside may not be warm at all. If this happens then you will know that your mug is not suited for microwaving.

The second thing that may happen is that your Starbucks mug may be warm and the beverage inside may be even warmer. If this happens then your Starbucks mug may be used for heating beverages.

It is worth mentioning that if the ceramic mug is lined with any metals then it should not be used for microwaving your beverages. 

What Happens If You Microwave Starbucks Reusable Cups?

Luckily, Starbucks reusable cups can be microwaved however there is a certain way to do so. To safely microwave your beverages in these reusable paper cups, set the microwave’s power to low or medium. Microwave for a maximum of 30 seconds to prevent damaging the cup.

These Starbucks reusable paper cups are lined with plastic that can be melted if heated to high enough temperatures. Even though you have the go-ahead to microwave them, please be careful when doing so.

Microwaves work by using radiation to vibrate the particles of substances causing them to heat. Paper cups contain tiny amounts of water molecules inside them which will break up when heated by the radiation from a microwave. When they break up this causes the walls of the paper cup to rip leaving an escape route for your coffee to leak out.

Not only will this be a mess for you to clean up, but now you won’t be able to reuse your cup in the future. If the microwave’s power is kept low and the timer is set to a max of 30 seconds then it is likely that you will avoid this catastrophe. 

Best Way To Reheat Your Coffee in a Microwave

The best way to reheat your coffee (or any beverage) in a microwave is to use a microwave-friendly container. Most of them will be marketed and labeled for microwaving so this is your best bet to prevent any unwanted accidents in the kitchen. 

If your beverage or coffee was in a tumbler and it got cold, simply retrieve one of these microwave-safe containers, cover it with a paper towel, and place it in the microwave for 30 seconds. If you prefer to drink from your tumbler then simply transfer the beverage or coffee back to your tumbler and enjoy. 

Even though it does take some extra work, this is the most convenient method of reheating your beverages for consumption. 


My final thoughts concerning microwaving your Starbucks tumblers are that you should only do so if the container is labeled as safe for microwaving. While you may be able to microwave the ceramic tumblers, you still need to be careful not to microwave the ones with double walls. 

Tumblers were created to hold beverages such as hot or cold coffee, and should only be used for that purpose. There are many containers available on the market that allow you to reheat your beverages safely in a microwave so it is best for you to use those containers. 

Also, Starbucks cups and mugs may be microwaved depending on the material. To stay on the safe side when microwaving, stick to ceramics and some paper cups. Microwave for no more than 30 seconds.

And there you have it; all you need to know about microwaving Starbucks tumblers. I hope this article was very helpful. 

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