Finding the best thermos flask can be a minefield. Choose the wrong one and you risk being lumbered with a cumbersome container with enough capacity for a shot glass of tea, while a nonchalant attitude to quality can be equally disastrous – nobody wants to discover that inadequate insulation has transformed their thermos of coffee into a flask of frappé.
Avoiding all these pitfalls is our top all-round pick for the best thermos flask right now: the Instagram-favourite Hydro Flask 32-oz insulated bottle. It boasts an extra-wide mouth and TempShield insulation, which eliminates condensation while keeping cold beverages cold for 24 hours and hot ones hot for 12 hours. It's on the pricey side though (although worth the investment, we think), which is why at number one in our list you'll find Klean Kanteen's Insulated TKWide Bottle, which has an identical capacity and a more wallet-friendly price tag.
If you're only going to be carrying cold drinks, you might also want to check out the options in our guide to the best reusable water bottles, and for insulated cup options, you might be better off in our best reusable coffee cup guide. If not, read on for our ranking of the best thermos flasks right now, plus the features you should be looking out for when you make your purchase.
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How to choose the best thermos flask for you
As much as we love a new type of insulation of a hi-tech finish, it's important to remember that the best thermos flasks aren't necessarily the ones packed with features. Start by taking a second to consider the flask's primary purpose. Are you using it for hot or cold drinks? While most thermos flasks will keep drinks hot or cold for a minimum of 12 hours, certain models offer hi-tech insulation (such as Hydro Flask's brilliant TempShield insulation), which keep cold drinks cold for much longer (up to 24 hours).
Consider which features you're most likely to benefit from. Handles on the lid are surprisingly useful, making it easy to attach flasks to rucksacks, while a powder coating is essential for style-conscious hikers who'd like to colour coordinate their thermos with their thermals. Wide mouths are a godsend if you're gulping on the go – although the best of both worlds is a double-layered cap which screws off in sections, to give you the choice of a wider mouth or a narrower one.
Finally, don't be seduced by unnecessary lingo, such as 'double-walled'. Most thermos flasks are double-walled – that's simply how they work. However, a growing number feature triple-walled construction, which is certainly worth considering if you're a hardcore hiker heading out into the wilderness for longer periods of time.
The Klean Kanteen Insulated TKWide is a colourful thermos designed with portability in mind. It's available in a range of colours and sizes (our pick is the 32oz thermos in lime green). The powder coating adds a grippy finish and ensures the bottle's exterior remains as vibrant as the day you bought it. The wide mouth – one of the widest we've seen on a thermos – makes it easy to drink from and fill up, and the unusual internal thread design on the bottle's neck results in an ultra-tight seal.
Although it's slightly on the heavy side, the pay-off is fantastic insulation – the flask will keep hot drinks hot for 22 hours, and chilled drinks cold for 75 hours – over three days. The flask is also incredibly versatile, with various extras for anyone keen to enhance its performance when it comes to specific drinks. The extra lids which can be purchased include a chug cap ideal for cold drinks, a cap designed to be used with a straw and a coffee cup-style lid for hot drinks.
The Hydro Flask Lightweight Wide Mouth is the best premium thermos flask right now. The lightweight build means that even when it's full to the brim of your favourite beverage, it won't weigh you down. What's more, it's packed with features which we wished we saw more of. There's a flexible carrying handle that not only increases portability but makes unscrewing the lid incredibly easy thanks to the extra purchase it provides. There's also an extra-wide mouth, which is especially useful if you're using it for cold drinks – you'll be able to quickly and easy drop iceberg-sized ice cubes into this flask. The extra-wide mouth also makes it wonderfully easy to clean.
Although some other flasks will maintain temperatures for longer, in our opinion, this flask offers the perfect balance between portability and insulation – it will keep hot drinks hot for 12 hours, and chilled drinks cold for 24 hours, and you'll struggle to find a thermos with similar insulating qualities and such a low weight. Keep an eye out for the best Hydro Flask deals to take the price down.
Typhoon’s offering might not boast the features offered by some of the more expensive models, but it’s a great option for anyone looking for an affordable, lightweight thermos flask to throw in their backpack for day hikes and jaunts to the beach. Its 500ml capacity means it will hold more than enough tea, coffee or water for two people, and it will ensure chilled drinks stay cool for 24 hours, and will keep hot drinks hot for 12.
An extra-wide mouth makes it easy to drop in ice cubes, and it’s also nice to see a thermos with an exterior design – all too many thermos flasks feature either unpainted stainless steel or a single block of colour.
This thermos is better suited to urban use than your next outdoor adventure. It'll only keep your drink hot for 5 hours – although that's plenty of time for your commute or wander round town, which is its intended use. It's also incredibly stylish, and thermos flasks that look this chic are in short supply. But don't get us wrong – the bottle has various features which we wish we saw more of, starting with its Autoseal button, which allows you to sip from the thermos without removing the lid, and using just one hand. Its low weight and slimline design – it comes in at just 315g – means it can be thrown in the smallest of bags without weighing you down.
If you're looking for an option for kids, try the Klean Kanteen Kid Classic Sport. This dinky but tough bottle comes in a range of bright designs, including prints and solid colours. The eco-friendly designs are BPA-free and chip resistant, with a lifetime guarantee. The sport version comes with a spill-proof sport cap with soft silicone spout, and a loop you can use to attach it to a bag. A nice touch is that this bottle works with a range of caps for different drinking abilities (including a leak-proof loop cap and a sippy cap), so it can be adapted as your child grows up. This isn't really a thermos, as it's non-insulated – although the single-walled design makes it lighter for kids to carry themselves, and is a great option for encouraging them to stay hydrated until they're ready for a fully-fledged thermos.