Freezers: How we test
We take more than 100 million temperature readings - one every eight seconds - to find our Best Buy freezers.
Recommended settings
We take readings from numerous positions inside the freezer.
We set up all the freezers according to the manufacturer’s recommendations and record how quickly the temperature drops to –18°C.
Using temperature probes inserted into 1kg packs of gel placed in different parts of the freezer, we check how well the temperature is maintained.
Because we know the moisture content of each pack, our results are consistent.
Temperature stability
As well as testing the freezers at room temperature (around 20°C) we also see how well each model copes with fluctuations in temperature in purpose-built climate-controlled chambers.
The rooms are lowered to 10°C to simulate temperatures in an unheated utility room and then raised to 32°C to re-create the effect of a hot kitchen.
Coping with power cuts
People outside large cities can suffer from an intermittent electricity supply. We test how long a freezer keeps food frozen in a power cut.
We load the freezers with gel packs and when they are all below -18°C we switch the power off. We then record the time it takes for any of the packs to rise to -9°C.
The best models keep groceries frozen for over 24 hours.
Storage options
We fill every freezer to meticulously check how much food each freezer can hold.
Manufacturers' capacity figures are often exaggerated because they do not take into account the space taken up by the plastic compartments, shelves and drawer fittings.
Frost-free models offer consumers greater flexibility because they often include large drawers so you can freeze big, odd-shaped items such as a whole turkey.
Noise annoys
A panel of independent experts rate how noisy each model is when it is freezing food. We look for more than just how loud each appliance is by paying special attention to how annoying the pitch and tone is.