There are certain things that always come in handy even if you aren’t using them regularly. An insulated thermos flask is one of them.
A thermos flask has two roles to play: keeping a drink warm or cold. If you are travelling in the scorching heat, you want to keep your beverage at its peak coolness. And we all know nothing beats the cold better than a hot sip of coffee. Today, we’re going to show you eight of the best thermos flasks of 2021. But before that, let’s see how a thermos flask works.
A thermos flask has a double-wall construction with a vacuum cavity between them. That vacuum cavity stops the heat from going out or coming in. Thus, the liquid inside of a thermos flask remains at the same temperature no matter where you are. A thermos flask won’t act like a kettle; you cannot boil anything in it. It will only keep a liquid warm or cold for a long period. The best thermos flasks can keep the liquid’s temperature stable for up to 12 hours.
Apart from using it at home, you can also help the world with the “go green” campaign. The next time you visit a coffee shop, take your thermos flask with you. Tell them to fill the coffee in it and avoid using their plastic coffee cups and maybe you might save a tree.
To choose the best thermos flask for you, we did our research and some practical work too. We poured both hot and cold liquids into the flasks and recorded how long each flask would last. To check how good a thermos flask is, we used a thermometer to test the temperature. Each flask was tested twice for half a day to check how fast they dropped or raised the temperature.
We made our list based on these results and some other relevant factors that we will mention below. Now let’s get down to business as we present the list of the best thermos flasks that you can find in 2021
Best Thermos Flasks of 2021
1. Stanley 18-8
The Stanley 18-8 is a double-wall stainless steel thermos flask perfect for a solo runner. It can carry up to 1 litre of any liquid, so even if you carry it with you for two days, your coffee will remain hot.
To help you get a better perspective on how good this thermos is, we put some hot water in it and tested the temperature over 12 hours. We documented that the temperature dropped from 84.6°C to 70.8 °C. We tested further by adding ice cubes to the water. The temperature dropped when we added ice cubes (2.8 °C to 1.7 °C) in 12 hours. But when we added only cold water, the temperature rose from 2.8 °C to 9.7 °C in 12 hours. Please bear in mind that this temperature may vary if you are travelling in more extreme climates.
The manufacturing company advertised the Stanley 18-8 as a thermos that can keep water cool for 24 hours. In real-time, we found that the water can stay cold for up to 5 days if you are not travelling to places with very high temperatures. In essence, if your temperature isn’t rising, chances are that the Stanley 18-8 is also cool as a cucumber.
The lid acts as a cup for those who love to enjoy their drinks slowly. There is a handle, and even if you shake the thermos, there is no leakage. This makes it a good fit for those who love to hike and travel.
The only drawback is the fact that it can’t take any more than one litre of liquid. However, that low capacity also reduces its weight and increases its portability. The weight of this flask is about 822g when empty, so it is almost 1.8kg in its total capacity. The head is not broad but wide enough to put in ice cubes to further cool your drink.
This thermos is also dishwasher safe. You can put it in the top rack of your dishwasher but make sure to remove the lid to clean it properly.
- Strong and durable
- Impressive heat and cold reservation
- BPA Free
- No Leakage
- Features a cup as a lid
- Low liquid capacity (only 1 liter)
2. OKADI Large Flask
Since we’ve introduced a flask that works for a single person, here’s something perfect for families. The OKADI Large Flask is not just for storing drinks, but you can also keep soups in it.
The storage capacity of 2.5L is more than enough for an entire family. The advertised time for cold products is 36 hours and 24 hours for hot products. But we didn’t just take them at their word.
As always, if you add ice cubes to the water, the temperature will drop, making the water cooler. But this time, instead of water, we used some peach juice. Surprisingly, the juice was able to stay cold for 36 hours, but it was not pleasing. However, you can add some ice cubes to keep it cooler for longer.
To test the heat, we used freshly boiled tea. After 28 hours, we saw a significant temperature drop. However, the tea was still warm enough to chug down instantly.
Keep in mind that thinner liquids will stay hot or cold for a longer time. While if you are using a thick liquid, it won’t last that long.
The dimensions of the OKADI Large Flask are 39.79 x 18.1 x 12.9. Quite reasonable for what it can hold. When it is empty, the weight is around 1.37kg and 2.8kg at its maximum capacity. Not idle for those who love to travel light. But perfect for those who love to travel with their family. There are two caps available in it, an excellent option for a couple who keeps forgetting cups at home.
Instead of having just two walls of stainless steel, they also added a copper wall. That single copper wall makes a significant impact on its performance, considering the size of this flask.
We tried shaking and throwing it around. Due to its weight, it won’t last long in rough conditions. But thanks to the silicon seal, there was no leakage. So, you are good to carry it in your bag or picnic basket without any tension.
- Dual cups
- Best for a family
- Large capacity
- Best value and quality for its price
- Not suitable for a solo user
- May not keep liquids hot for too long
3. WayEee Food Flask
Thermos flasks are not just to store liquid. There are some thermos’ that you can use to keep food warm. The WayEee Food Flask is big enough to keep your soup warm for a reasonable amount of time. However, since it is enormous, you can expect it to keep food warm for around six to ten hours.
It also comes with its own small sized bowl and a spoon. WayEee Food Flask is available in two different variants – 450ml and 710ml. It has double insulated stainless steel. Thus it is lighter than the OKADI flask but does the job well.
The large size of this flask can keep food for two people easily. And with extra attachments, you don’t need to bring plates and spoons. Moreover, you can store water or juice in it, but it can work for soup and other food.
Like other large flasks, we tried our test using soup and peach juice. It is advertised to keep food hot or cold for six to eight hours. But in our test, the soup needed an oven after 5 hours, but the juice stayed cold for over nine hours. If you add ice cubes to the juice, it will last even longer. Thanks to its large size, it is excellent for small travelling picnics. But if you are going further, I suggest you try the OKADI large flask.
In my opinion, coffee and cold water will stay hot or cold for an even longer period. But since it has only two stainless steel walls and a big mouth. Whatever is inside is sure to lose its state early.
Weight is not a problem here. The 450ml variant weighs around 337g, and the 710ml variant weighs about 350g. So, if you are going for a hike of one or two hours, you are good to take this with you. Comparison in weight, this flask is the lightest one available. However, in terms of storing capacity, it is the smallest one.
WayEee Food Flask features an anti-skid silicone mat, so it won’t stay adrift for long if you slip it. You can use the cup to store more food, or it can act as an extra plate for serving. Apart from travelling, you can also take it to the office but make sure to finish the food within six hours.
- Three years warranty
- Excellent heat retention
- Large capacity for food
- Folding spoon
- It can be hard to open
4. GSI Outdoors Microlite 1000 Bottle
Colours do impact a person’s choice since men and women have different options of colours. GSI Outdoors Microlite 1000 Bottle stands out at specific points but one of its best features is its availablility in 7 different colours.
You need to perform a solid twist to open the lid. And the cup is connected to the bottle so that you won’t lose it quickly. The loop around the neck can be attached to the bag or used as a handle.
We tried using hot and cold water for this test. For starters, this thermos is advertised to keep liquid hot or cold for up to 18 and 32 hours, respectively. We conducted our test for half a day only, and the results weren’t surprising.
The temperature for hot water dropped from 88.5°C to 69.3 °C in 12 hours. It is close to competing with Stanley 18-8, but not the winner.
We didn’t add ice cubes for cold water, so the temperature dropped from 2.9 °C to 10.1 °C in 12 hours, which is excellent.
The best part of GSI Outdoors Microlite is its weight. When it is empty, it weighs around 370 grams. And when it is filled with water or tea, the total weight is around 1.37KG. Keep in mind that the number 1 (Stanley 18-8) flask in our list weighs around 1.8kg. This stainless steel bottle is the next best option for hiking, especially if you love to try different colours.
GSI Outdoors Microlite is not as light as advertised, but it sure is more lightweight than others we have mentioned. You can pick it up, and you’ll instantly feel the difference. It has a rugged and compact design that most people love while hiking. The twist cap and push top design work well to keep the heat in. However, this bottle is best for thin liquids like tea or water. For coffee, you can just store your hot water in it and make coffee as you go.
- Very lightweight
- Works extraordinary well for solo hikers
- Available in different colours
- No attached cup for drinking
- No extra capacity variant
5. Hydro Flask Water Bottle Wide Mouth
If you’re the type that loves to drink lots of water, then the Hydro Flask Wide Mouth is the best option for you. It can store up to 1.81L of water and is advertised to keep liquids hot or cold for 12 and 24 hours. But if you put it to the test, things can get a little different.
First, I tried adding cold water to it. The temperature of the water when we filled the flask was 5°C. After 12 hours, the temperature had risen to almost 10°C, which is pretty good and is still good enough to drink.
After that, we conducted a hot water test. The starting temperature was 92.3°C. After 12 hours, the temperature came down to almost 58.3°C. So for hot water, I won’t recommend this flask. But it is excellent for those who hog down a lot of water daily.
The surprising part of this thermos flask is its weight. Although it has a storage capacity of 1.8L, it only weighs 72g when it is empty. That was the biggest surprise for me since it is enormous as compared to other flasks. For colours, you can choose between blue and cobalt.
If you fill it to the top, the entire weight is around 2kg. This is still bearable considering how much water you can put in it. This one item is a perfect option for an average user and someone who’ll use it for hiking.
The lid is leak-proof since you can twist to close and open it. There is a carrying handle at the top; you can attach it to your bag. And even if your bottle is upside down, your contents will remain dry in your backpack. Hydro offers a lifetime warranty, so you are free to throw it around. And surprisingly, the colour remains intact even after getting scratched.
- Different sizes available
- Huge storing capacity
- Can keep water hot for up to 12 hours
- BPA free
- It is expensive
- No cup, despite its size
6. Thermos Mondial Flask
If you prefer your drinking water filtered, then the Thermos Mondial Flask might be the best option for you. Apart from this stash compartment, it is available in different colours.
Mondial Flask is made from plastic and glass. So it won’t be a good option for hiking, but for family trips, it is excellent. You can keep the exterior clean easily since it is made of glass. And that plastic is there to give it a solid but subtle touch, and it works like a charm.
Weight is a bit of a problem where this weight is why it is not suitable for hiking. Mondial Flask weighs around 910 grams when it is empty. And it has a storage capacity of 1.8L; a total weight of around 2.7 kilograms. That’s a lot of weight to carry around, in our opinion, which makes it a little impractical for long hikes. There are other options available, though. We particularly liked the one with a 1liter storage capacity. It was more good looking as well.
The advertised time to keep hot and cold water is around 12 hours to 24 hours, respectively. The stash compartment lets you add a different flavour to your water. And if you want to enjoy a little taste of tea? You can add a stash of tea there, slowly pour water into a cup, and enjoy light taste tea.
- Features two cups for drinking
- Large storage capacity
- Available in 3 different colours
- Twist and pour stopper
- 1-year guarantee
- The shipping is not reliable
7. Thermos 185515 Light and Compact Flask
Thermos flasks were supposed to keep the body at an average temperature. However, in some cases, we have seen people complaining about their flask temperature. So, if you have ever experienced such a problem, you can switch to Thermos 185515, a lightweight and compact flask that does its best to keep the water cold and hot as you want.
The best part of this flask is that its outer body remains cool, so you can easily touch it even with piping hot water inside of it. However, it is available in 2 colours only, midnight blue or stainless steel.
The entire body of Thermos 185515 is made of stainless steel. The company even added a stainless steel cup for extra comfort. You can drag it around or throw it anywhere, and it will survive. So for your next adventure, this thermos can be helpful. Or, if you want, you can make it your partner for the daily commute.
The rubber sealing cap on this thermos also has a pop-up opening so that you won’t chug down the entire bottle in one gulp. This mechanism also keeps it away from leaking no matter how much you shake it. Even if you put it upside down or lying on the table, you can relax about the leakage.
Thermos 185515 weighs around 530g, not the lightest one available, but not the heaviest one either. You can easily carry it around or put it in your backpack. Since there is no leakage problem, your bag will stay dry all day long.
The biggest surprise about this thermos is it can keep both hot and cold water for up to 24 hours. The company advertised it like that, we haven’t tested it, but it is new. Other thermos flasks have a difference in keeping hot and cold water, but Thermos 185515 outperform them all in this aspect.
- Durable
- Cool to touch
- Push-button stopper for easy pouring
- Sweat-proof with cold
- The screw-on cap is a little fragile
- No handle
8. SMARDY Vaccum Insulated Water Bottle
Looking to get a budget-friendly thermos flask? Then this SMARDY flask is the best you can get. It does all the stuff other flasks can do in a low price range. However, it only has a storage capacity of 430ml, which is enough for two cups of tea.
This product is suitable for those who want to keep themselves hydrated. However, if you’re someone who drinks a lot of water every day, it would be best if you found a flask with more storage capacity as this one will run out fast.
But if you look at it, you can use this flask for multiple activities. You can carry hot water for 2 cups of coffee. Or you can simply make the coffee and pour it in the thermos and give yourself a boost throughout the day. You can even save the Starbucks plastic waste by letting them pour coffee right in your bottle.
The SMARDY flask is made from high-quality stainless steel. That makes it quite durable, and more likely to last a long time. The vacuum portion of this bottle is covered with silver coating, thus preserving more heat inside the bottle. There is a rubber sealing on the bottle top to prevent leakage when the bottle is closed.
The temperature performance of SMARDY can last about a day. The cold water stays cold for 24 hours, and the hot water stays hot for almost 12 hours. However, you can also pour juice, tea or coffee into it, and they’ll keep their temperature for a long time. One thing to notice is that liquid like water will stay hot/cold for a longer time. At the same time, liquid-like soups or milk might not remain the same for long. So, take your pick based on what you are taking.
- Easy to carry
- Leak-proof
- Cheap
- Multi-purpose
- Only available in 430ml variant
Choosing the Best Thermos Flask
To give the customer the best product, we conducted our research like a customer. Certain things are universal, and everyone would look for them. However, certain factors are necessary, but people tend to overlook them. Thus, they end up getting a product but not the satisfaction they were looking for. What’s the point of having something that won’t perform as you want?
During our search for the best thermoses, we performed carefully arranged tests. For instance, we checked the thermometer after every hour to see how fast the liquid temperature was dropping.
The weight of the thermos flask is a crucial factor. We also examined whether the lid of the bottle is loose after we put it through some brutal use. So we are pretty sure that our list of best thermos flasks is enough for you to make a decision.
However, should you choose to do your own research, here are some factors you need to keep in mind.
Temperature Performance
The most prominent reason to get a thermos flask is because it can retain a liquid’s temperature. If the thermos flask is not doing this one job, it’s basically useless. So while we prepared the list, we did some tests and made sure that all of the products are working fine. We did tests to check the temperature drop and then put them on our list.
You need a thermos flask that can keep water cool or hot for at least 12 hours. All the listed products have this feature, so you can scroll up and check them out.
Material
The construction of a thermos flask is everything. If it is not built strongly to survive any impact, you might end up destroying it quite quickly. Since these outdoor thermos flasks are made for hiking and travelling, the material used for the build must be rigid.
Furthermore, most flasks have two walls surrounding the vacuum, but some are made with three divisions. The cost will increase as more walls increase the quality of the thermos. So, if you are looking for a cheap one, you might want to stick with one that has only two walls.
Cup as Lid
This feature is perfect for those who love to sip coffee while travelling. Since you cannot drink coffee right off the bottle, you need a thermos that features a vup as its lid. That way, you can cool down the coffee a little if it is smoking hot for you.
Moreover, if you are keeping water or any other cold drink in your thermos, you can share it with another person by pouring it into the glass and keep them away from your flask.
Ease of Use
Let’s say that your thermos flask has a loose lid. Can you fix it easily? If you can fix it quickly, you don’t have to worry about getting another thermos for this simple problem. If the thermos flask has a handle, that’ll make it easy to carry in case you can’t put it in the bag.
All of these small features add to a thermos’ ease of use. It can mean the difference between a thermos suited for the kitchen or one that can survive your adventure in nature.
Wide or Narrow Mouth
If you are not going after the cup-lid thermos, then it would be best if you chose between a narrow or wide mouth thermos flask. But how do you choose one? In simple terms, if you want to carry water with you, then a wide mouth thermos is perfect. But if you are taking some energy drink or juice, then a narrow mouth thermos is perfect.
Frequently Asked Questions
1. How do I clean a thermos flask?
Well, some thermos flasks are approved for dishwashers. You can put the cap and the thermos in the top drawer of the dishwasher and let it clean. However, not all of them are safe for dishwashers, so you need to separate their parts and clean them individually.
Start cleaning the body first since it takes the most amount of time. Be sure to remove the rubber from the lid and clean it properly. There are chances that some food is stuck there. Then you can clean the cap and let them both dry. Once dried, put them all in the same place or simply put them together again.
2. What are the best thermos cups?
There is no such thing as an all-in-one package. Every product has something that could be improved. We have presented the complete guide with the best thermos flasks available; however, the best one for you depends on your needs. If you want to have lots of water, then you can choose the Hydro Wide-mouth flask. But if you want to travel light, you can select Stanley 18-8. It depends on how long you want the liquid to stay hot/cold and how much you want to drink.
3. Which thermos stays hot longest?
That depends on what sort of stuff you want to keep hot. If it is water, it can stay hot for up to 24 hours or even more. But if it is something thick like soup or milk coffee, it might get cold within 6-10 hours. Still, keeping something hot for 6 hours is enough. Any longer than that and you’ll have to worry about the taste as well as the temperature.
4. Which thermos flasks are better; stainless steel or glass?
To put it simply, stainless steel flasks are much better than traditional glass ones. Stainless steel is durable and easy to clean. Even if you drop it, there will be minor damage. And the vacuum put between the stainless steel walls is best for keeping liquid temperatures regular.
5. What is the difference between a thermos flask and a vacuum flask?
These two terms refer to the same type of thermos. Thermos flasks have two or three stainless steel layers (inner and outer). Between those walls is some space called a vacuum. Since there is no air in it, it won’t affect the temperature inside the flask. Due to that vacuum, it is called a vacuum flask. If you are to purchase a thermos flask, but the packaging says “vacuum flask”, they pretty much mean the same thing.
6. Can a thermos explode?
There is a good chance that a thermos can explode or even implode. If the pressure inside the flask is reaching extreme and you won’t open it, the flask will explode. Secondly, if the flask’s inner layer is compromised, it might implode on its pressure. Both can cause injuries and burns if there is hot liquid inside the flask.
But you can check if there is a problem. The easiest way is to check the cap; if it is uncommonly tight, we have a problem. Put the flask away from you and gently tap the lid on all sides. If the top is stuck, wait until the liquid gets cold, and the cover will open easily.
7. Is it safe to put boiling water in a thermos?
Yes, the whole purpose of a thermos flask is to keep the boiling water hot. But make sure that you are using a stainless steel thermos for better safety. The glass thermos is easy to break due to high temperature. Moreover, the stainless steel vacuum flasks are best when it comes to heat retention.
8. How does a vacuum flask work?
All vacuum flasks have insulated stainless steel layers in them. One on the outside and one on the inside. Between those layers is a vacuum. That vacuum is responsible for not letting the heat out. And thanks to that vacuum, nothing from the outside can affect the contents inside. So your hot or cold beverage can retain its temperature. The advertised time that most companies mention is 12-24 hours, but it can be more.
9. What do I do if the thermos is leaking?
The best answer is to get it replaced. But you need to check the leakage spot. If it is leaking from the body, then send it for replacement instantly. But if it is leaking from the cap, check whether you have placed the rubber seal properly. Some people complained about the leakage after they washed the flask. In such cases, the rubber seal on the cap is loose and thus causing leakage.
Final Words
Due to rising competition, we see cheap and nasty versions of everything. Even if you are purchasing a thermos flask, you might end up getting an affordable product. However, that product may not have what it takes to keep you satisfied. Imagine that the cold water you put in your thermos 4 hours ago is no longer in the same state. You are craving some cold water, and now all you have is frustration.
Companies may advertise the temperature retention time of 24-32 hours for cold drinks. But a sub-par flask won’t even last for 5-6 hours. Moreover, there are chances of leakage. If you put a leaky flask in your bag and the bag has documents and your laptop, you might end up paying a lot more than you should for any flask. .
We have compiled the list of the best thermos flask you can get in 2021. All these flasks have different functionalities, some are for hiking, and some are for an entire family. You can store water in them, and some have the potential even to keep soup warm. So if you are going for a picnic, these flasks can help keep your food warm.
Really appreciate the list, OutdoorMag. Was on the lookout for a good thermos for my hiking trips. The Stanley 18-8 caught my eye – seems like it could take a beating on the trails. Has anyone tried it out in colder climates?
Can anyone recommend which of these flasks are easiest to clean? With two toddlers, I don’t have time for complicated care instructions. Thanks in advance!
I’m curious about the insulation tech in the WayEee Food Flask. Does it use vacuum insulation or something else? And how does it perform with both hot and cold foods?
Last year, I took the Hydro Flask on a week-long trek across the Appalachian Trail. Handled both the heat and cold like a champ. Definitely recommend for anyone who’s into serious hiking.
For all my fellow coffee lovers, the Thermos 185515 Light and Compact Flask has been a game changer. Keeps my java hot for hours. Any other coffee thermos recommendations out there?
Does the SMARDY Vacuum Insulated Water Bottle really keep drinks cold for 24 hours? Need something reliable for long days at the office.
Are any of these flasks made from recycled materials or particularly eco-friendly? Trying to make responsible choices.
I’ve used both the GSI Outdoors Microlite and the Hydro Flask on different trips. The GSI is lighter, which is great for backpacking, but Hydro Flask keeps my drinks cold for longer. Depends on your priorities.
Jules, would you say the GSI’s weight advantage makes it the better choice for long hikes? Weight is a big deal for me.
Absolutely, Barry. If you’re hiking long distances, every ounce counts. The GSI hasn’t let me down yet!
For anyone wondering about cleaning, a mix of vinegar and baking soda has always worked for me to get rid of any flask stains or smells. Just make sure to rinse well.
Absolutely love my WayEee Food Flask for keeping my meals hot when I’m out for a hike or at the gym. Curious if anyone has found a good way to pack salads or cooler foods? Would love some tips!