Best flasks and travel mugs that will keep drinks hot (or cold) for hours

Lukewarm tea is no longer a concern when you have a good flask. In some cases, these heat-trapping vessels can preserve the temperature of your drink for more than 24 hours, so whether you’re headed to the great outdoors or tackling a chilly commute, they’re a must.

For longer excursions, opt for built-in cups like those from Klean Kanteen and Thermos, and mouthpieces that allow quick, drip-free and sometimes one-handed sips for when you’re on the go, such as the push-to-open design of Contingo’s flask. Flasks aren’t just for holding water or a brew – we’ve even tested a flask specifically designed for holding a bottle of wine. It’s perfect for picnics.

Ultimately, what makes a flask worth your money is its ability to slow down heat transfer – either in or out – via a layer of almost airless space sandwiched between the flask’s inner and outer walls.

Keep reading to find out which flasks impressed us the most.

How we tested

First and foremost, flasks had to keep drinks hot or cold to make it onto our list. We assessed the brands’ claims by filling the flasks with boiled and iced water, then drinking from them hours later to see if the temperature held.

We also considered how easy the flasks were to use, assessing mouthpieces, lids, handles and more. They also had to be leak-proof.

Why you can trust IndyBest reviews

Lois Borny has been part of the IndyBest team since 2021. She has written about household essentials, fashion, and a whole lot more in between. When testing items, Lois factors in quality, value for money and, ultimately, whether they're effective. If she doesn’t think a product is worth buying, it won't make the cut. In other words, every flask here has been put to the test in the real world.

The best insulated flasks for 2025 are:

• Best overall – Thermos superlight drinks flask, 470ml: £22.94, Amazon.co.uk
• Best compact flask with a cup – Lifeventure TiV vacuum flask, 700ml: £22.99, Lifeventure.com
• Best for style – Stanley quencher H2.0 flowstate tumbler, 1.2l: £36.27, Amazon.co.uk
• Best insulated mug – Hydro Flask coffee mug, 354ml: £28.95, Amazon.co.uk
• Best hi-tech flask – Larq bottle purevis, 500ml: £89, Livelarq.com