Freezers: How we test freezers
How Which? tests freezer temperature
Recommended freezer settings
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, 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 more than 24 hours.
In all, we take more than 100 million temperature readings – one every eight seconds – to find the Which? Best Buy freezers.
Storage options
We fill every freezer to meticulously check how much food each model can hold.
Manufacturers' capacity figures are often exaggerated because they don't 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
A panel of independent experts rate how noisy each model is when it is freezing food.
Energy Saver logo
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.
Our Energy Saver award is given to Best Buy freezers that meet our own energy-efficiency criteria and is designed to help you choose products that use less electricity compared to other products of the same type that we've tested.
For freezers, we test for energy efficiency then rank the results and award the Energy Saver logo only to Best Buys whose energy use is in the top 20% of all the models we've tested, with separate rankings for tall, chest and counter-height models.
The Which? Energy Saver logo is a Which? rating and is not in any way endorsed or associated with official EC labelling laws or regulations. For advice on understanding the official EC energy label on products see our guide energy labels explained.
We look for more than just how loud each appliance is by paying special attention to how annoying the pitch and tone is.
