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When you get one of those precious days of sunshine and outside looks to be the best place for your dinner and drinks, a quality cooler bag is essential.

We tested cooler bags in April 2021, including household favourites Thermos, Argos, and a premium version from cooler bag specialists, Yeti. We put the bags through their paces across a number of areas including insulation, durability and how leakproof they are. 

We looked at how comfortable they were to carry and at the quality of their design. And to get a better understanding of their capacity, we filled each cooler bag full to the brim with drinks cans.

Pricing and availability last checked as of 4 August 2022.

Only logged-in Which? members can view the cooler bag test results below. If you're not yet a member, you'll see an alphabetically ordered list of the cooler bags we tested. Join Which? now to get instant access to our test scores and Best Buy recommendations below.

Size (HxWxD): 33x30x30cm  

This cooler bag from Argos is the cheapest we tested. The bag has a simple boxy, polyester design with no bells or whistles. 

Log in or join Which? to find out how the Argos cooler bag compared with its pricier competition. 

Cheapest price: £19 at Amazon ,Blacks , Go Outdoors , Millets

Size (HxWxD): 36x35x25cm

Key features: Waterproof, leakproof, available in 20 and 25 litres

This 30-litre cooler bag doesn’t have the extra compartments, mesh holders or dividers seen on some of the other bags, however it does have a unique inflation ability. But did this make a difference to its insulation or is it just a gimmick?

Join Which? or log in to find out. 

Only available at Mountain Warehouse : £16.99

Size (HxWxD): 26x35x26cm  

Key features: Additional mesh and zipped pockets, leakproof

One of the cheaper bags we tested, but it still has additional features such as mesh pockets, velcro straps for condensing and zipped pockets. 

Extras aside, want to know how it did in our testing? 

Join Which? Or log in to find out. 

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Size (HxWxD): 31x36x28cm  

Key features: Additional pockets, two-year guarantee, leakproof, available in six litres and 16 litres

Polar Gear claims to have heat-sealed lining to avoid leakages. But how did it actually do in our leakage test?

To find out login in or join Which? .

Only available at Decathlon : £19.99 (20L model)

Size (HxWxD): 33x35x33cm  

Key features: Mesh pockets, two-year warranty, available in 20 litres

This cooler bag from Decathlon has a compact design allowing it to be easily condensed for storage. It also claims to keep contents cool for nine hours without the use of ice packs, but did our testing confirm this?

To unlock our results join Which? or log in. 

Size (HxWxD): 32x33x27cm  

Key features: Additional mesh pockets and zipper pockets, 12-month warranty, leakproof, water-resistant, available 8.5 litres and 16 litres

Thermos boasts its own unique IsoTec insulation – essentially, compact foam insulation within the walls of the main bag. It has an easy access lid, mesh pockets and additional zipped pockets.  

We’ve tried and tested Thermos flasks but how does the Thermos cooler bag compare?

Log in or join Which? To find out.

Cheapest price: £30.99 at Costco , also available at Amazon .

Size (HxWxD): 30x35x25cm 

Key features: Additional mesh pockets and zipped pockets, lifetime warranty, leakproof

The Titan Deep Freeze cooler bag looks rugged and – with a number of extra compartments, mesh pockets and extra straps – it would appear to be the perfect bag for a camping trip. 

To find out how it did in our insulation test and to see whether it’s as rugged as it looks join Which? or log in. 

Cheapest price: £17.99 at Vonhaus , also available at Amazon , 

Size (HxWxD): 23x43x24cm  

Key features: Additional pockets, two-year warranty, leakproof, available in 22 litres

The only bag we tested with a hamper-style design. The cooler bag is held up by a rigid aluminium frame attached to a handle. This construction makes it great for storing away, but what’s its primary function like? 

Log in or join Which?  to find out. 

Size (HxWxD): 37.5x31x18cm  

Key features: three-year warranty, leakproof, waterproof

Yeti is renowned for its high-performance cooler bags and this is reflected in the price – the Hopper Backflip 24 is the most expensive of the bags we tested. Its backpack design makes it a great option for chilling on the go. It also claims to be leakproof, waterproof, and have the ‘toughest zipper in the world.’ 

But just how tough was the Yeti cooler bag? Join Which? or login to find out.   

We got in touch with some cooler bag brands and our fridge expert to see if they had any tips on optimising your packing technique. 

Here’s what they had to say:

1.   The difference in temperature change across the bags wasn’t huge. There was only a 2.7°C difference between the bag that heated up the most and the bag that heated up the least. 

So, while there was a winner, none of the bags were particularly bad at insulating. 

The Food Standards Agency recommend that you keep your fridge set at 5°C so that cold food stays at around 8°C. 

Though our water bottle temperatures were higher than that, temperature is relative and the more ice packs you use the cooler the bag will be. If you've got perishables, particularly food, you should be ensuring your cooler bag is 5°C or below.

2. Great insulation can be nullified by poor design. The bag that came out top in the insulation test was also the only bag to leak.  

3. A good zipper can make a world of difference. An easy-to-use zip means you can get in and out quickly avoiding hot air getting in and cold air getting out. We found that two bags had stiff zips. 

One was so tough it became a chore to open and another caught on the inner lining, eventually ripping it off.

We put 11 cooler bags through their paces across a few key areas. 

We put a chilled bottle of water and an ice pack into each bag. The ice packs were kept in the freezer overnight and then left in the bags for 30 minutes before testing began. We attached thermocouples (a sensor for measuring temperature) into each bottle and left them for the day, taking temperature readings on the hour, every hour. 

To replicate typical use, we opened and closed the bags four hours in – and then every 30 minutes.

We filled the bags with 500ml of water and left them sitting on top of a bed of paper towels for an hour. After the hour we checked for any leakage onto the towels and poured the water back into the measuring jug to see if any had been absorbed by the towels.

We identified the stress points of the bags – usually the handles and straps – and tugged at them 10 times each. We carried out a visual inspection before and after to see if the bags incurred any damage.

We filled each bag with half their capacity in cans and carried them along the same route for five minutes. 

We noted any extra features each bag had and tried the zips at the beginning and at the end of testing to see if they had been affected by our tests.

For our test we picked cooler bags that were strictly bags, not boxes. They had to be made of soft material.  

We then focused on bags that were more suitable for larger groups. Our research showed that a 'family size' bag typically falls into the 20 to 30 litre range. 

We ordered and paid for all the cooler bags that we tested. Which? doesn't accept freebies, which gives us the freedom to tell the truth about our test results.