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LOOKING for a way to keep your favourite meals piping hot while you’re out and about?
The best food flasks are the ultimate solution for anyone who loves a hearty soup, a warming curry, or even their overnight oats on the go.
In summer, they’re a great addition to your camping supplies, and they’re also ideal for keeping salads crisp and refreshing during the morning commute.
We’ve done the hard work for you and rounded up the top food flasks that tick all the boxes — keeping your meals hot (or cold) for hours, being leak-proof, easy to clean, and, of course, stylish enough to carry around without embarrassment.
We’ve tested a range of food flasks to ensure they deliver on performance, practicality and price.
Whether you need one that can handle a heavy-duty hike or simply something to keep your leftovers warm at your desk, we’ve rated them all so you can make an informed choice.
How we tested the best food flasks
We tested six food flasks over the course of a couple of months, using them to take food into the office.
We also compared their heat retention abilities by filling them all with an equal amount of boiling water, then checking intermittently to see which ones kept it the hottest over the course of a day.
The best food flasks, at a glance
Zwilling Thermo Food Jar
Thermo Food Jar, £34.95 £27.96 from Zwilling with code JUNE20
Pros: Includes stoway spoon, lid can also be used as a bowl, big 700ml capacity, dishwasher safe, lightweight considering its size
Cons: Bulky design makes it less portable than some competitors, only comes in two colours
Rating: 9.5/10
This is a proper bit of kit. Measuring 17cm in height with a 10cm diameter, it’s the biggest flask we tested, which might put you off if portability is a key consideration.
However its 700ml capacity means it should satisfy even the biggest appetites, and considering its capacity, it’s also very lightweight, clocking in at half a kilo.
It’s also really cleverly designed; like the Thermos flask below, it comes with a stowaway spoon, but Zwilling goes one step further; the lid doubles up as a bowl, making it easy to share your food.
It performed outstandingly in our tests, keeping water warm for a really impressive length of time. After almost three hours, the water was too hot to physically touch, and after seven hours, it was still piping hot.
And — this will be a theme in this roundup — the Zwilling flask gets a big tick for being dishwasher safe, meaning you don’t have to wash it up by hand after a long day at work.
Our only tiny niggle is that it’s perhaps not as fashion-forward as some other flasks — it only comes in two colours, white and black — but to many shoppers, that won’t matter.
Material: Stainless Steel; Capacity: 700ml; Weight: 500g Dishwasher safe? Yes
Thermos Icon Series Food Flask
Icon Food Flask (470ml), £25 from Thermos
Pros: Competitively priced, comes in a wide range of colours, comes with a stow-away spoon, dishwasher-safe
Cons: Slightly heavier than some competitors, narrow mouth makes it slightly hard to eat
Rating: 9/10
Thermos is likely the first brand name that comes to mind when you think of food flasks.
After all, the word has become synonymous with keeping food and drink warm; people are as likely to call one of these a “Thermos” as a “food flask”, no matter what brand it is.
This flask is from the brand’s “Icon Series”, which it claims “blends a legacy of quality with advanced insulation”.
The result is a sleek, stylish metal food flask that comes in an array of colours; we opted for Ice White, but there’s a few lovely options available.
There’s also a 710ml option available if you’re feeding two (or one very hungry person).
The Thermos was one of two flasks we tested that includes a stowaway spoon cleverly stashed beneath the lid; it’s a lifesaver if you’re camping, and it could even come in handy if you’re too lazy to get up and get a spoon at the office.
It’s also one of only a couple of flasks we tested that is dishwasher safe, so it gets bonus points for that.
In our test, it was the best performer when it came to heat retention; the water was still too hot to touch a full seven hours after we put it into the flask.
It’s also a full £10 cheaper than the Zwilling, making it the perfect choice if budget is a key consideration.
Our only two niggles were that it’s the heaviest model we tested, and because the mouth of the flask is quite narrow, it’s not the easiest to eat from.
Material: Stainless Steel; Capacity: 470ml; Weight: 510g Dishwasher safe? Yes
Black+Blum Food Flask
Black+Blum Food Flask, £31.95 £23.59 from Healf
Pros: Comes with a spoon and elastic strap, sleek metal design, impressive heatkeeping capabilities
Cons: Tall and narrow design can make it slightly hard to eat certain foods, 0.4L capacity might be too small for hungrier people
Rating: 8/10
It’s a tiny thing, but we love that Black+Blum straps a chic wooden spoon to its food flask; it’s a nice touch, and makes sure you won’t be left in a situation where you’ll be forced to slurp food straight out of the jar.
It’s also very nicely designed, with a sleek metal construction.
While the metal finish certainly looks nice, we were worried that it would leave the flask vulnerable to scratches and dings, but after a couple of uses, it still looks as good as new.
That’s backed up by the reviews on the Black+Blum site, with one person writing that their flask “has been in constant use for two years and is still in perfect condition”.
It really impressed in our boiling water test; six hours after we first put boiling water into it, when the water in many other jars was tepid, the water in the Black+Blum flask was still steaming.
Our only tiny qualm was that Black+Blum has chosen a taller, narrower design, compared to the short and wide shape opted for by Le Creuset and Hydroflask, which makes it slightly harder to get to the food at the bottom of the jar.
However, it does make it more portable, and it could probably fit into the water bottle compartment of most backpacks.
Material: 304 Stainless Steel; Capacity: 400ml Weight: 370g; Dishwasher safe? No
Chillys Stainless Steel Food Pot
Original Stainless Steel Food Pot, £28 from Chillys
Pros: Looks sleek, can be personalised, lightweight, decent heat keeping capabilities
Cons: Not dishwasher safe, metal finish is easily marked
Rating: 7/10
Chillys bottles are as much a status symbol as anything else, and the brand’s Food Pot looks just as sleek.
Ours came in a brushed metal finish, which looks really nice, but we’d probably go for one of the other colours if we were to buy one; the metal was quite easily marked, and we could see it getting quite battered quite quickly.
We suspected that, like the Le Creuset pot, it could be a bit style over substance, but we were pleasantly surprised by its heat-keeping capabilities.
I’ts also one of the lightest food flasks we tested, which could be an important factor if you’re ferrying it to work every day.
However, it’s not dishwasher safe, which caused us to dock some points.
Being a Chillys product, it’s also super giftable, and the brand leans into that by adding the option to engrave a name on the flask for £10.
Material: Stainless Steel; Capacity: 500ml; Weight: 389g Dishwasher safe? No
Le Creuset Food Jar
Food Jar, £35 from Le Creuset
Pros: …it’s Le Creuset, lovely ridged design, double threaded opening prevents leaks, not badly priced considering the brand name
Cons: Didn’t retain heat as well as other models
Rating: 6.5/10
We’ve got no qualms in admitting that we were drawn to this food flask thanks to the brand name and design.
Embossed with Le Creuset on the side and adorned with the three concentric rings that the brand usually puts on its ceramic lids, it certainly looks the part.
It also comes in four of the brand’s iconic colours: Cerise, Shell Pink, Satin Black and Deep Teal.
All come with a sleek metal lid that contrasts nicely to the hard plastic jar.
It’s the best of both worlds; the combination looks sleeker than a flask entirely made of plastic, but it’s likely to look fresher for longer compared to a full metal flask, which is prone to scratches and dents.
With a 10.7cm diameter and a height of 12.4cm, this fits firmly into our preferred “short and stout” category, giving you enough width to get to the bottom of the flask without too much effort.
However, in our highly scientific tests, we did notice that it lost a lot of heat through its lid, resulting in only lukewarm contents after six or so hours.
Material: 304 Stainless Steel; Capacity: 500ml; Weight: Not stated Dishwasher safe? No
Hydro Flask 20oz Insulated Food Jar
Hydro Flask 20oz Insulated Food Jar, £36.19 from Amazon
Pros: Large capacity, dishwasher safe, wide diameter makes food easy to eat, soft grip lid is super easy to open
Cons: Doesn’t look as sleek as other flasks, easily marked
Rating: 5.5/10
If we were to design a food jar, this is the shape we’d go for: short, stout and wide, making it easy to eat your food without getting your hands messy (it also makes it easier to clean).
If you’re eating somewhere cold, the design might mean you lose heat a bit faster, and it’s perhaps not as portable, either, but personally, that’s a sacrifice we’re willing to make.
The Hydro Flask also won a place in our hearts thanks to being dishwasher safe; most food flasks aren’t, and it’s a dream to be able to throw it in with your dinner plates after a long day at work.
Hungry shoppers will also appreciate this flask’s 20oz (591ml) capacity, and the soft-grip lid is a nice touch, making it easy to open even if you’ve got wet or greasy hands.
Initially, it impressed in our testing, too; unlike some other flasks, you could barely tell there was boiling water inside; the outer still felt cool to the touch.
However, after six hours, the initially boiling water was only tepid, which was disappointing. In fact, it lost heat more quickly than any other flask we tested.
Another (admittedly shallow) complaint is that it perhaps looks a little less chic than other food flasks. After all, every day is a fashion show.
It was also quite easily marked, the purple finish getting scuffed with black marks after just a couple of journeys to work.
Material: 18/8 Stainless Steel; Capacity: 591ml; Weight: 420g; Dishwasher safe? Yes
How long does a food flask keep food warm?
This depends heavily on which one you go for.
Thermos claims that its Food Flask keeps food warm for up to 14 hours, and we believe it; we were blown away at how well the brand’s food flask retained heat.
We filled it with boiling water at 9:30am, and at 4:30pm the contents were still too hot to handle.
Less sophisticated flasks may only be able to keep food hot for half that long, but you should expect that, if you prepare hot food before you come into work, it’ll still be hot at lunchtime, six or so hours later.
It’s best to pick a flask size that aligns as exactly as possible with your appetite, because in an ideal world, you want to fill it to the top — empty space can cause heat loss.
What can I put in a food flask?
You can fill flasks with a variety of foods, depending on your needs.
Hot meals such as soups, stews, pasta, or even curries are popular choices, as the insulation ensures they remain warm until you’re ready to eat.
For breakfast, porridge or oatmeal works well, especially when topped with fruits or nuts.
If you prefer cold options, food flasks are perfect for salads, yoghurt, or chilled treats like overnight oats.
Drinks such as tea, coffee, or hot chocolate can also be stored in certain flasks, provided they have the appropriate seal.
When packing food, ensure it’s preheated or pre-cooled before placing it in the flask for maximum effectiveness — some brands even recommend you rinse them with boiling or cold water first to boost their heating or cooling abilities.
Cut items into smaller portions if necessary, as this helps with even heating or cooling. Avoid carbonated drinks, as the pressure build-up could damage the seal.
How do food flasks work?
Food flasks use vacuum insulation to maintain the temperature of their contents.
The walls of the flask are typically made from stainless steel, with an airless vacuum layer between the inner and outer walls.
This vacuum acts as a barrier that prevents the transfer of heat or cold between the inside and the outside of the flask.
When hot food or liquid is placed inside, the vacuum insulation minimises heat loss, keeping the contents warm for hours.
Conversely, when cold food or drinks are stored, the same technology prevents external heat from warming the contents, maintaining their cool temperature.
