Can You Put A Thermos In The Microwave?
Whether or not you can place a thermos in a microwave is one of the most controversial questions there is.
While it generally is believed that you cannot or should not place this metal-based container inside this metal-opposed appliance, many people argue otherwise.
So, what is it then? Can you put a thermos in the microwave? Bottom line, while many people say yes you can, we say that it isn’t worth the risk — there are just too many variables that cannot be proven or disproven at this time. Instead, opt for alternative products that are either microwave-safe or can keep your drinks and food warm for an entire day.
Today, we will be looking at exactly why people say you can place a thermos inside a microwave — and why we say you probably shouldn’t. But at the end of the day, it’s up to you!
Can You Really Put A Thermos In The Microwave?
Now, we all likely already know why it is commonly believed that you shouldn’t put a thermos inside a microwave.
This storage container is made from metal, usually stainless steel, and metal does not get along with microwaves.
When this material is placed inside a microwave, it can cause sparks. In turn, these sparks can cause an explosion or fire.
So, why is it then that more and more people say you can use your thermos inside a microwave?
We are first going to look at the arguments for this question, then some known counter-arguments as to why you shouldn’t. But ultimately, the choice is up to you.
We recommend taking a look at our product list below for some great thermos alternatives.
They might not work as efficiently as a thermos, but they will still keep your food warmer than a plastic container and can be 100% safely used inside a microwave.
Reasons Why You Can Put A Thermos In The Microwave
We aren’t advocating for this team, but we of course had to familiarize ourselves with their reasoning. So, here are the reasons some people argue you can use a thermos inside a microwave.
1. The Stainless Steel Is Very Thick
Many people argue that the reason metal (like aluminum foil) creates sparks and causes explosions is because of how thin it is.
So, because a thermos has significantly thicker metal walls, they say it won’t heat up nearly as much and, ultimately, will never cause sparks.
2. A Thermos Doesn’t Have Corners
Next, it is believed that sharp corners and edges of metal objects are a lot more likely to cause sparks. There are a bunch of video experiments that you can look at online that seem to support this claim.
So, because a thermos is completely round with no edges, they think it won’t be as likely to create a spark.
3. The Lid Is Open
Because you open the lid of the thermos when heating its contents, they argue that there isn’t an excessive amount of pressure build-up that can lead to explosions.
Reasons Why You Shouldn’t Put A Thermos In The Microwave
Now, as you may have already guessed, there are still more reasons why you shouldn’t do it. And honestly, our stance remains that it isn’t worth the risk.
Yes, many videos show people microwaving round, thick, metal objects without any issues. But we think that the risk is still too high — not to mention how energy-inefficient it is.
Have a look at some of the most important reasons microwaving a thermos is dangerous and, quite honestly, inefficient.
1. How Thick Are The Walls Really?
Honestly, there is no way to accurately tell how thick the walls of a thermos really are. So, what if, by Murphy’s law, you bought a product that actually has pretty thin walls? Is it worth the risk?
Plus, most of the experiments are done with pure stainless steel objects. What if your thermos has been made with a more reactive metal?
2. The Food Or Drink Will Heat Unevenly And Slowly
It is a known fact that everyone said when doing their experiments — because of the thick metal walls, the food takes forever to heat up!
Plus, the only area where heat can enter the container is at the top, which is usually quite small compared to the volume it contains. So, is it worth it?
3. The Term “Highly Unlikely” Is Used Too Often
This is something that bothers us a ton when people try to disprove a mostly proven claim. The term used in all these “yes you can” articles is “highly unlikely” — so, that means there is still a chance that things could go boom.
We know for a fact that metal is reactive in microwaves. Isn’t that enough reason to not take the risk?
When people say “highly unlikely,” they’re basically saying “it’s not our fault if something goes wrong even though we’re trying to convince you otherwise!”
It’s a dangerous term to throw around and we think it makes their claims less believable. If you’re not willing to back up your statement with surety (and science), you cannot expect others to take that risk.
Alternative Products To A Traditional Thermos
If you’re on team “I’d rather not risk it” with us, then here are some alternative products you can try that will keep your food warm — most of them are even microwave-safe!
| Rank | Product | Key Features |
|---|---|---|
| 1 | THERMOS Microwavable 12-Ounce Food Jar | This is a thermos food container with a microwave-safe inner container. It is easy to use, carry, and clean. |
| 2 | Mora Double-Walled Microwave-Safe Travel Coffee Mug | The perfect ceramic-based microwave-safe double-walled travel mug that can be used to keep your drinks hot or cold for long periods. |
| 3 | S’well Stainless Steel Triple Layered Travel Mug | A stylish triple-insulated travel mug that keeps your drinks hot or cold for the entire day! |
| 4 | YBOBK HOME Insulated Thermal Bento Box Microwave Safe | The ultimate stackable divided thermos lunchbox with an inner microwave-safe plastic container. |
1. THERMOS Microwavable 12-Ounce Food Jar
The first alternative on our list is a food storage container made by THERMOS themselves — the design is unique as compared to traditional food jars!
This food jar consists of two parts.
On the outside, it is made from stainless steel that helps to insulate the food inside. It can keep the food hot for around 4 hours and cold for up to 6 hours.
Then, you also get the inside of the jar — this is a separate, removable container made from Tritan co-polyester. This plastic container is what you can place inside the microwave safely!
The food jar has a 12-ounce capacity and is simple in design, but efficient in function.
The mouth of the jar is wide enough to easily put food in it, and it also allows more heat to penetrate the food as it heats. So it will heat quickly and evenly!
2. Mora Double-Walled Microwave-Safe Travel Coffee Mug
Next up, we have a special travel mug! Now, we know there are hundreds of thousands of travel mugs out there — not all of them are actually insulating or work as efficiently as a thermos.
This travel mug from Mona has an extremely thick silicone ring that helps enclose the contents and keep the heat in.
It is double-walled, meaning heat escapes less quickly, and it’s also made from ceramic clay, which is excellent at retaining heat.
And before you worry too much, the ceramic is super durable and hard. It’s not going to crack easily. And the glaze is made from 100% lead-free and all-natural materials.
So, seeing as there is no metal in this thermos-like mug, you can safely place it in the microwave and dishwasher! Just remember to remove the lid so your hot drink heats up efficiently without building up pressure inside.
3. S’well Stainless Steel Triple Layered Travel Mug
This is another type of travel mug. However, this is not a microwave-safe option. So, why did we include it on our list?
Well, unlike most travel mugs made from stainless steel (like a thermos), this one is triple-insulated. That makes it even more effective at keeping your liquids hot or cold while you’re on the go!
We have a similar triple-insulated travel mug (sadly, it’s old and has since been discontinued) that leaves out drinks hot for an entire day! That means that you don’t even have to reheat the drink.
Last but not least, this travel mug seals tightly. You can toss it in your bag without worrying about spills or leaks. It’s an amazing product that we highly recommend. And it’s super stylish!
4. YBOBK HOME Insulated Thermal Bento Box Microwave Safe
And finally, we have this amazing stackable Bento lunchbox set!
The outside covering of the stacked containers is all made from food-grade stainless steel — naturally, this part cannot be placed in the microwave.
However, one of the stacks comes with an inner food container made from microwave-safe BPA-free plastic.
This set will allow you to divide different elements of your meal and even keep them at relatively different temperatures. If you’d like, you can use the thermos feature to keep your food warm.
And the entire stack comes with an easy-to-carry bag. The bag offers even further insulation, making the overall product highly effective.
