Whether you need a vessel for your morning coffee or something that would be right at home in Bear Grylls’s backpack, an insulated flask is a game changing bit of kit when it comes to portable home comforts.
Preserving temperatures for hours, you can find flasks best suited for everything from frosty commutes and picnics (think wine cooling containers) to weekend camping trips. But they all work in the same way, with a vacuum cavity between the inner and outer layer slowing down the transfer of heat.
While larger flasks with intergrated cups (Thermos king, we’re looking at you) are perfect holding for inordinate amounts of tea and soup, smaller flasks make practical, sustainable and cost-effective swaps from single-use coffee cups and are cleverly designed for one-handed, splash-free sipping.
Then there are insulated flasks that are much more suited to keeping drinks cold. These are a great way to encourage yourself to drink more water if you prefer your beverages refreshingly chilled (or even iced during the summer). Luke-warm bottled water? No thank you.
Many of the vacuum flasks we tried were able to keep drinks piping hot for up to 12 hours with some even surpassing the 24 hour mark. All could manage up to at least five hours which, if you simply want to keep your coffee from going cold till lunch, is all you really need.
How we tested
Naturally, temperature preserving ability was our main priority when testing these, which we assesed by filling the flasks with recently boiled water and sipping after the maximum temperature preservation time stated by the brand, to see how our hot water had fared. We used the same methods with iced water and cold drinks.
While sipping out and about or around the house, we also paid attention to whether the mouthpieces, sipping mechanisms and lids were easy to get grips with, while portability was determined by weight and packability. They all had to be leak-proof to make the cut.
The best insulated flasks in 2023 are:
- Best overall – Thermos stainless steel king flask: £29.95, Amazon.co.uk
- Best environmentally conscientious flask – Ocean Bottle: £35, Oceanbottle.co
- Best value for money – Lifeventure TiV vacuum flask: £22.99, Lifeventure.com
- Best for keeping water cold – Chillys series 2 lichen: £30, Chillys.com
- Best small flask – Stanley classic trigger action travel mug: £31.99, Stanley1913.com