MieleKFN 4397 CD

How we test chilling power

We test how quickly a fridge chills, as the faster food cools the longer it will last, the more nutrients it will retain and the less chance there is for harmful bacteria to thrive.

How we test ease of use

To see whether a fridge freezer is easy to use, we rate aspects such as how sturdy the shelves and drawers are, how smoothly the drawers slide in and out, whether there are enough door racks and shelves for the size of the machine, whether the fridge freezer is easy to programme and whether the thermostat is easy to adjust.

How we test ease of cleaning

We spray cherry juice inside each fridge, let it dry to a sticky mess and then rate how easy it is to clean, to see how likely food and drink spills are to seep into hard-to-reach spots and crevices.

How we test freezing power

How quickly it can freeze, or how much it can freeze in one go. The greater the freezer power, the faster it will freeze your food - minimising the chance for bacteria to grow and helping ensure food is as fresh and nutrient-rich as possible when you defrost it.

How we test temperature stability - hot rooms

We test how closely the fridge freezer maintains the correct temperature when the room temperature rises, just as it does in your kitchen at home during a heatwave. We do this by turning the temperature in our test chamber up to 35°C and testing the temperature of the food-equivalent gel packs. Five stars means the gel packs stay perfectly chilled and frozen, which is what you want for your food. But two stars or less means the gel packs either warm up or become too icy in the fridge compartment.

How we test recommended thermostat setting

To see whether you can rely on a fridge freezer's thermostat to create perfect temperatures for storing chilled and frozen food, we set the appliance up following the manufacturer's recommended thermostat setting. Models scoring five stars have reliable thermostats that are spot on, whereas models scoring two stars or less would need to be set up using a separate thermometer to adjust the temperature.

How we test energy efficiency

How energy-efficient the fridge freezer is for the amount of usable space it offers. Fridge freezers are switched on 24/7, so it's important to choose one that won't cost a fortune to run. The best models score four or five stars and use a minimal amount of energy to cool food. You can spot the real energy guzzlers as they're awarded a poor one or two stars in this test.

How we test quietness

We rate how quiet and unobtrusive the sounds made by each fridge freezer are when the compressor's running and when it switches on and off.