Best thermos for keeping hot drinks warm and cold drinks cool

A thermos will keep your chosen beverage at the perfect temperature wherever you are.

best thermos

by Rosie Floyd |
Updated on

The best thermos will change the way you enjoy your favourite drinks on the go. They’re designed to ensure your hot drinks stay steaming hot and your cold drinks are ice-cool whenever you want to take a sip. Whether you’re craving a warm cup of instant coffee to perk you up on your morning commute or a refreshing sip of cooling water after working up a sweat, a thermos will ensure your desired beverage is served to you at the temperature it should be whenever you need it.

You may be wondering how does a thermos work in order to keep your drinks hot or cold when needed. Essentially, they trap heat or cold inside a double-walled vacuum-sealed chamber that is typically made of stainless steel or glass, which acts as an insulating barrier to prevent the heat or cold from escaping. They’re also typically equipped with a tightly sealed lid that prevents air from getting in or out of the thermos to further minimise the heat or cold transfer. The combination of vacuum insulation, double-walled construction and a plastic or rubber-sealed lid works to effectively keep the temperature of your chosen beverage hot or cold for hours on end.

Best thermos at a glance:

• Best thermos overall: Thermos Stainless King Flask – Buy now on Amazon UK
• Best leak-proof thermos: Stanley Adventure Stainless Steel Thermos – Buy now on Amazon UK
• Best thermos for durability: YETI Rambler – Buy now on Amazon UK

As well as their effectiveness in keeping the temperature of your drinks just how you like them, the best thermos will have a range of user-friendly features to enhance your overall drinking experience. Think leak-proof seals to stop unwanted spillages in your bags and lids and spouts that you can effortlessly sip or pour from, as well as ergonomic designs that make them comfortable to hold in your hand and carry with you while on the go.

By investing in a thermos, you’re not only able to enjoy the convenience of being hydrated with your favourite drinks on the go but you’re also doing your bit for the planet as by using a reusable coffee cup/water bottle you're helping with reducing the waste caused by single-use plastic bottles and cups. Whether you’re navigating the bustling city streets on your daily commute or exploring the great outdoors on the weekends, the best thermos will ensure you have a hot or cold drink to hand in whatever adventure you’re tackling.

Best thermos for hot or cold drinks

Best thermos overall

Thermos Stainless King FlaskThermos/Amazon

Rrp: $49.99

Price: $40.49

Taking the top spot is the brand we all think about when it comes to thermoses and flasks, Thermos. The Thermos Stainless King Flask's vacuum insulation technology offers maximum temperature retention so it'll keep your tea, coffee and hot chocolate nice and hot for 24 hours and your water or squash cold for 24 hours too. If you're using this Thermos for hot drinks, you won't need to worry about scalding your hands with it as it's designed to stay cool to the touch with hot liquids inside.

For the quality of the flask, customers across the board felt the handle could be better as it's a little bit flimsy. However, with over 21,000 reviews and an average star rating of 4.7, it's loved for being easy to use, hold and clean, as well as being leakproof.


  • Keeps hot hot and cold cold for 24 hours
  • Exterior remains cool to the touch even with hot liquids inside
  • Durable stainless steel interior, exterior and cup


  • Some reviewers felt the handle should be as sturdy as the rest of the flask

Best leak-proof thermos

Stanley Adventure Stainless Steel ThermosStanley/Amazon
Price: £35.31

Regardless of whether you're tackling a walking trail in the summer or heading off on your morning commute in the winter, the Stanley Adventure Stainless Steel Thermos is made for keeping hot and cold drinks warm or cool wherever you go. It's designed with a leak-resistant lid so you can pop it in your bag and be safe in the knowledge you're not going to end up with a pool of liquid collecting in the bottom of it when you reach for it later on.

When it comes to feedback from real-life customers, the Stanley Adventure Stainless Steel Thermos is described as being solid and well-made and that it does an excellent job at keeping drinks warm for a long period of time. One reviewer even said their tea was still hot even 24 hours later after being kept inside. There is some confusion about the dishwasher-safe elements of this thermos as the product listing describes the whole thing as being dishwasher safe, however, a reviewer found that only the lid and stopper inside are, so that's just something to be mindful of when it comes to cleaning.


  • Keeps liquids hot or cold for up to 24 hours
  • Leak-resistant lid to spot spills
  • Easy to clean


  • The Amazon listing says this product is dishwasher safe but a reviewer found that only the lid and stopper inside are

Best thermos for durability

YETI Rambler YETI/Amazon
Price: £24.95

Made with kitchen-grade stainless steel, the YETI Rambler is built to last as it's puncture and rust-resistant. As it's more robust compared to some on the market, dents and scratches shouldn't show up as easily so, if consider yourself to have butterfingers, it won't damage easily if you accidentally drop it. Combine this with the leak-proof lid, double-wall vacuum insulation to keep drinks the temperature they should be and 'no sweat' design that stops condensation from building up on the outside, you've got yourself a good all-round drinks flask.

The leakproof lid of this thermos gets a huge thumbs-up from customers. In fact, on just that factor alone, customers rated it 4.9 stars out of 5. They also appreciated that the thermos combines style and functionality so you're not just getting a one that looks good but it does a good job too. Options are mixed on the overall value, with some thinking it's expensive for what it is, but we think it's worth splashing out when you look at the overall quality you're getting for the money.


  • Very durable as it's made from kitchen-grade stainless steel
  • 'No sweat' design so your hands won't get wet from condensation
  • Leakproof lid to stop drinks for spilling


  • Capacity is equal to one 'coffee-shop-sized' drink so not ideal if you're going to be out and about all day

Best thermos for style

Chillys Liberty Tropical TrailChillys/Liberty

Pretty meets practicality with the Chilly’s Liberty Tropical Trail cup. Made in collaboration with iconic British retailer Liberty, it features a stunning tropical print so you can drink your cup of Joe with style each day. The rubber base at the bottom of the cup helps with the stability of the cup if it accidentally gets knocked and it also means you can put it down silently compared to other thermoses where you might hear the clunk of the stainless steel hit the table. It also has an antimicrobial drinking surface which is designed to help keep the nasty bacteria away in between cleans.

The thing that lets this thermos down for us is that it only keeps drinks hot for up to four hours, which isn't very long compared to others on our list. You would still be able to take your morning coffee with you to enjoy on the go and it stay warm for the duration of your commute though.


  • Pretty and practical
  • Rubber base for stability
  • Antimicrobial drinking surface


  • Designed to keep drinks hot for up to four hours so this could be longer

Best thermos for compact size

Hapi FlaskHapi/Amazon
Price: £12.99

Rushing around in the morning and don't have time to fit in your much-needed tea or coffee before you leave the house? The Hapi Flask is perfect for taking your favourite beverage with you on the go as it's made in a cupholder-friendly size. Its features include a push button opening and a safety lock so you'll have peace of mind that it's not going to spill liquid everywhere when you're not drinking from it.

We, as well as customers online, love that it comes in 350ml and 500ml capacities and a choice of eight colours so you can stay stylish as well as hydrated. As well as loving how it looks, customers rated the Hapi Flask highly for its overall quality and appreciated that it arrived well-packaged.


  • Perfect size for cupholders so you can take it in the car with you
  • Non-spill safety features on the lid
  • Choice of colours and capacity
  • Easy grip for those with arthritis


  • Some reviewers felt it wasn't completely leakproof

Best thermos for one-handed operation

JUMKEET Double Walled Vacuum Cup FlaskJUMKEET/Amazon
Price: $11.99

The JUMKEET Double Walled Vacuum Cup Flask boasts a one-hand-operated lid so even when you've got one hand full, you can flip the switch and sip while you carry on with whatever task you're doing. It has a curved design so it fits nicely and comfortably in your hand and when it comes to cleaning it up, it's very easy to disassemble so you can scrub each individual part.

You may not have heard of the brand JUMKEET before, but this thermos comes highly rated on Amazon with over 4,000 reviews and an average star rating of 4.3. Options are mixed when it comes to how leakproof it is. Some people found it did leak water and coffee when it was placed in their bag whereas other have found it to be 100 per cent leak proof.


  • Curved, ergonomic design for your comfort
  • One-hand lid operation
  • Highly rated


  • It insulates heat and isolates cold for about 12 hours, which while still impressive is less time than some of the others on our list

Best thermos for easy cleaning

YJH Double Walled Vacuum Insulated BottleYJH/Amazon
Price: £13.99

Featuring a carry handle and an insulated cap that doubles as a cup, the YJH Double Walled Vacuum Insulated Bottle is a great choice for drinking hot and cold beverages on the go. It can also be used for soup if needed. When it comes to keeping it clean and free from bacteria that can lurk on uncleaned water bottles and thermoses, it comes with a cleaning brush with a long handle so you can get into all the nooks and crannies in the lid and cup as well as reach down inside to the bottom of the thermos.

Opinions are mixed on how leaky it is. Some found it did leak the drinks out but others have had no issues with it. Some reviewers also wished the cup was a little bigger as they felt it was a bit small compared to the overall capacity but that just means you'll feel like you're getting more cups of tea and coffee out of it in the long run.


  • Can be used for soup as well as drinks
  • Has an insulated cap that can be used as a cup
  • Comes with a sponge for easy cleaning


  • Some reviews found it to be a bit leaky but others have had no issues

Best eco-friendly thermos

Ocean Bottle Brew FlaskOcean Bottle

Using a reusable thermos rather than single-use bottles is good for the planet but if you want a thermos that's great for the planet, consider the Ocean Bottle Brew Flask. It’s made from 90 per cent recycled stainless steel to start with but for every Ocean Bottle bought, the company funds the collection of 1,000 ocean-bound plastic bottles so you can savour every sip of your tea and coffee guilt-free. The lid is not only leakproof but also has a 360 design so you can take a swig of your drink from any angle.

As well as the fact it's environmentally friendly, customers on Trustpilot liked that the Brew Flask is aesthetically pleasing while keeping their drinks nice and hot. Some reviewers thought the capacity could be bigger and we agree as it's one of the smaller capacity thermoses on our list. Some also found that it was hard to tell when the lid was closed and they experienced some leakage when it wasn't shut properly but when the lid is fully shut, it is completely leakproof.


  • Eco-friendly option
  • 360 lid to drink from every angle
  • Made using recycled materials


  • Some reviewers felt the capacity could be larger


Which brand thermos is best?

Any of the thermos from our list would be a great option for your next thermos but if you’re basing your decision of the best thermos on its temperature-maintaining qualities, we’ve found that both Thermos and Stanely do some of the best thermoses on the market from our research. Both the Thermos Stainless King Flask and the Stanley Adventure Stainless Steel Thermos will keep your hot drinks warm and cold drinks cool for up to 24 hours and they both have capacities of one litre or above so you can enjoy multiple drinks throughout the day at a consistent temperature.

As the Thermos Stainless King Flask has a larger capacity compared to the Stanely and is designed to remain cool to the touch no matter how hot the liquid inside is, it’s made the top spot for the best thermos that you can use take with you as part of your lunch box at work or out-and-about on outdoor adventures.

Why does my flask not stay hot anymore?

There are a couple of reasons why your thermos flask may not be keeping in the heat as much as it used to. This can be due to general wear and tear to the insulation inside your flask from years of cleaning and being exposed to high temperatures or if you’ve accidentally dropped or damaged your thermos in any way, cracks, dents and scratches can cause heat to escape so the contents inside doesn’t stay as hot. Your flask could have also developed issues with its sealing mechanism, which can cause your flask to leak while letting in cold air, cooling the liquid inside.

The age and overall quality of your thermos may also be what is causing your liquids to get cold more quickly. No flask is designed to last forever so it could just be that it’s reached the end of its lifecycle if it’s quite old or if you opted for a cheaper flask, the insulation may not be as effective compared to ones with a higher price tag.

Is plastic or steel thermos better?

Whether you're using your thermos as a water bottle or a flask, generally speaking, steel thermos tend to be better than plastic ones. They are typically more durable and offer better insulation so they can keep liquids hot or cold for longer periods of time while also being a bit more resistant to damage from accidental drops. Plastic thermos are often lighter compared to stainless steel ones so they may be better for someone looking for a flask to take with them on outdoor adventures. Plastic ones don't tend to dent or scratch as much as stainless steel ones so if you are a bit clumsy and tend to drop your thermoses or water bottles, the damage won't show up as much.

How can I best clean a thermos?

For advice on how to clean your thermos, we've got advice from the originals when it comes to creating thermoses and that's the brand Thermos. They say to ensure your thermos remains in tip-top condition, you should hand wash it as dishwashers use harsher detergents and hotter water that may affect the appearance and performance of your thermos.

You should wash all parts of your thermos thoroughly with warm soapy water, rinse and allow time to dry to get it looking squeaky clean again. Be careful not to immerse or soak your thermos in water for prolonged periods of time as residual contents may become trapped between the individual components of your chosen thermos. You also should avoid using bleach or cleaners containing chlorine on any part of your thermos and don't use abrasive cleaners or cloths either as they may dull the finish and damage the insulation.

Rosie Floyd is a Pets, Homes and Garden Product Writer for Yours, specialising in home appliances, décor and furnishings, as well as all things dogs. After completing her Journalism & Media degree from Coventry University back in 2015, she started her career writing about must-visit holiday destinations, moving on to creating content around outdoor living and garden buildings, before joining the team at Bauer.

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