How we test fridges

We use gel packs and temperature probes to test cooling speed

Which? fridge tests

A great refrigerator will chill your groceries fast to keep them fresher for longer, and keep food at a consistent temperature when your kitchen heats up or cools down. It will run quietly, offer plenty of useable storage space, and won't add a fortune to your energy bills.

To find the models that fit this bill, we carry out up to 215 checks, measurements and tests on each fridge at our temperature-controlled labs. 

To see the Which? verdict on the latest fridges, head straight to our fridge reviews.

Fridge cooling power

The faster your groceries chill to below 5°C, the longer they’ll last and the more nutrients they’ll retain. To challenge fridges we set the room temperature to 25°C and part-fill the compartment with gel packs to simulate the items already stored in your fridge.

Once the fridge has acclimatised, we add 6kg of gel packs – roughly equivalent to a small fresh-food shop of 12 tomatoes, four pints of milk and a whole chicken - and use temperature probes to record the time taken for them to reach 5°C.

We also record the temperature of gel packs on the top, middle and bottom shelves and check how much the temperature varies - if your fridge doesn’t cool evenly across all of the shelves it could have warm pockets of air and icy patches, which could cause your food to spoil.

Fridge storage space

The more storage space inside your fridge, the more groceries you can pack away and the less frequently you’ll need to shop. Yet two appliances of the same size might have more than 20% difference in usable space due to differences in design.

We measure storage space with all of the storage features in place and don’t count any wasted areas. Our sizes give a more realistic indication of the amount of space you can actually use for storing groceries, compared with manufacturers’ claimed capacities - which are usually measured with all of the shelves, drawers and water dispenser removed.

Fridge energy costs

Running a fridge over its lifetime can be expensive – because it’s always switched on you will constantly pay to power it. We measure how much energy each fridge uses over 24 hours in a 25°C room, then calculate what this will add to your yearly energy bill.

To compare the true lifetime costs of fridges, combining the purchase price and running costs over several years, check out our energy costs calculator tool.

We also rate each model on energy efficiency - the amount of energy each fridge uses to cool the usable storage space available. This shows you whether each model is energy efficient for the space you’re paying to power. 

For products that successfully marry Best Buy performance with superb energy efficiency in our in-depth tests, we’ve introduced our Which? Energy Saver logo - you can find out more about how this is awarded in our guide to fridge energy costs.

Ease of use and cleaning

Some fridges are easier to set up and use than others. We rate the type of display, position of the thermostat control and how easy it is to adjust, and whether it comes with a quick-chill switch or door-open alarm. To find out more about the the various features you may find on a fridge read our features explained guide.

We also rate how sturdy the drawers or compartments are, how easy they are to open, how easy the appliance is to clean, the quality of the storage features and whether it's frost-free. In total, our expert testers carry out up to 86 ease-of-use tests on each fridge.

And, because it's virtually impossible to spot how noisy a fridge will be while you're in the shop, our independent testers rate not only how loud each fridge is when it's cooling, but also how annoying the pitch and tone are.

thermostat 2

We test whether the thermostat will accurately set your fridge running at 0-5°C 

Thermostat settings and temperature stability

Most fridge instruction manuals come with a setting or guide for positioning the thermostat - but following these doesn't always lead to ideal temperatures for keeping food safely chilled.

When we set a fridge up in our test lab we follow the recommended setting, allow it to acclimatise and record the temperature of gel packs inside. This tells us how cold food would actually be if you plugged the fridge in 'straight from the box' without checking the temperature with a fridge thermometer.

The best appliances will chill the packs to 0-5°C - first time. The worst will run too warm or cold, and need lots of thermostat-tweaking to get the running temperature right.

We also test temperature stability - because room temperatures can vary widely over the course of a day and at different times of the year. To do this we raise the temperature in our test chamber to 32°C, then we lower it to a chilly 10°C. We measure how stable the internal temperature remains - good fridges should stay between 0-5°C.

Fridge  scores explained

Fridge total test scores ignore price and are based on: 

  • Accuracy of recommended thermostat setting 10%
  • Fridge temperature evenness 20%
  • Temperature stability 25%
  • Cooling speed 10%
  • Convenience 10%
  • Noise and vibration 10%
  • Energy use 15%

Fridge testing changes for 2012 

The weekly shop is a thing of the past – when we surveyed 1,841 Which? members in August 2011 we discovered more than 90% of members add fresh food to the fridge several times a week, and most keep it nearly full most of the time.

So at the beginning of 2012 we changed the way we test fridges to match this habit more closely. Now when we assess how quickly the fridge compartment chills fresh groceries to 5°C, we make sure the fridge is already nearly full, relative to its size. The fridges in our test labs now have to work harder to chill fresh food, just as they do in our fridges at home. We’ve also raised the typical ‘room’ temperature in our test chamber from 20°C to 25°C to see how well each appliance keeps cool when it’s forced to use more energy, just as it is in your kitchen.

Plus, we’ve changed the way we rate energy use in light of rising energy costs and because fridges are becoming more efficient. We’ve increased the amount that energy use contributes to the final score, and made it harder for fridges to score three, four or five stars.

For fridges tested before 2012, the score was based on the same total test score as above, but temperature evenness contributed and energy use contributed 25% and 10% respectively.  

Though you can generally compare results for fridges tested before 2012 with those tested after (this is noted under the specifications tab in each review), the results don’t directly correspond. However, each score still gives a very good indication of the overall performance of the fridge.

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