In this guide (7)
The months printed on frozen food packs only hold at 18 degrees below zero, and that is not a rule of thumb but a regulated value: 87.94% of the four star compartments in the European registry declare exactly that temperature. We read 37,085 records, the Bosch manual and the regulation to work out the stars, the freezing capacity and the hours of autonomy without power.
Your freezer has a dial or a display with a number that was set once and never touched again. The packaging of frozen food has a little table with rows of stars and a number of months beside each one. The two things are connected, and that connection is the only piece of information that really matters: those months only hold if the inside sits at 18 degrees below zero.
We at PortosEunostos started from the European EPREL registry, 37,085 household appliances with a frozen food compartment, and placed it next to the user manual of a Bosch freezer and the regulation that decides those stars. Four numbers come out of it, and one of them is not printed on the energy label.
What temperature a freezer should be kept at
The short answer is 18 degrees below zero, and it is not a rule of thumb: it is a regulated value. Annex IV, table 3 of Regulation (EU) 2019/2016 sets the target temperature of a freezer compartment at exactly that level, and every European product information sheet declares the recommended setting for that compartment.
Across the 36,229 four star compartments we pulled from the registry, 31,858 declare precisely 18 below zero, or 87.94%. Only 2.54% go lower and 2.99% sit higher. So there is no "right" temperature to hunt for model by model: there is a single value, the freezer is designed to reach it, and dropping to 20 or 22 below costs electricity without meaningfully extending the life of the food.
The stars are not a rating, they are a temperature scale
The stars printed on the door do not measure how good the appliance is: they state the temperature that compartment can hold, with the values written into the same regulation.
Zero stars or ice making: 0 degrees.
One star: 6 degrees below zero.
Two stars: 12 degrees below zero.
Three stars: 18 degrees below zero, but for storage only.
Four stars: 18 degrees below zero and the ability to freeze fresh food.
The gap between three and four stars is the most important one and the least explained in store. A three star compartment holds the same temperature as a four star one, but it is not rated to freeze fresh food: it can only keep food that is already frozen. In the registry 1,080 household appliances, 2.91%, have a frozen food compartment but no four star compartment, and 622 of those are three star. More to the point, 831 out of 1,080 are fridge freezers, the machines people buy assuming they are getting a real freezer. If the question for you is the cooling system rather than the stars, we took it apart in No Frost or static refrigerator.
How long food really lasts at 18 below zero
Here the right source is not hearsay but the manufacturer's manual. The Bosch user manual for built in freezers gives a plain table, valid at a constant temperature of 18 degrees below zero:
Fish, cured meats, cooked dishes and baked goods: up to 6 months.
Meat and poultry: up to 8 months.
Fruit and vegetables: up to 12 months.
The sentence that counts is the one under the table: the printed freezing calendar states the maximum storage time at that constant temperature. If the freezer averages 14 or 15 below because it is overpacked, because the door does not seal or because the room is warm, those months no longer apply. It is not the food that expired early: it is the appliance that failed to hold the condition those months are calculated on.
The same manual is blunt on another point: food that has thawed fully or partly must not be refrozen. After a power cut, throw away anything that went above 5 degrees; anything merely softened has to be cooked first and only then frozen again.
How many kilos you can freeze in one day
Freezing capacity is the number almost nobody looks at and the one that decides how you shop. It states how many kilos of fresh food the compartment takes from room temperature down to 18 below in 24 hours. The regulation requires at least 4.5 kg per 100 litres of volume, with an absolute floor of 2 kg.
Across 34,152 records that declare both volume and capacity the median is 6 kg a day, but the value depends almost entirely on size:
Up to 80 litres: median 2.7 kg in 24 hours.
80 to 130 litres: 6.0 kg.
130 to 200 litres: 10.0 kg.
Over 200 litres: 14.0 kg.
Two practical consequences. First: 17.11% of records declare a capacity within 50 grams of the legal minimum, designed to pass the test and nothing more. Second: with a 64 litre undercounter unit such as the Smeg FF08EW, which declares 3.3 kg in 24 hours, a full shop takes two or three days to freeze, while a 212 litre built in such as the Bosch GIN81VEE0 declares 13.8 and clears it overnight.
The manual adds the condition that makes that number real: super freeze has to be switched on 4 to 6 hours before loading at least 2 kg, and around 24 hours before if you want the full declared capacity. It switches itself off after about 60 hours.
How many hours a freezer holds without power
This figure is not on the energy label. It is called storage time in case of power failure and it sits in the technical sheet of the individual model. Across the four Bosch and Siemens built in freezers we opened, the declared values are 8 hours for the 212 litre No Frost, 9 hours for the 85 litre and 13 hours for the 72 litre static: the smallest model holds five hours longer than the largest. If you live somewhere with frequent outages, that number matters more than half an energy class.
PortosEunostos tips
What to check on the product. In order: four stars and not three, freezing capacity in kg per 24 hours measured against your weekly shop, hours of autonomy without power, a temperature alarm, and automatic or manual defrosting. On that last point the market is split down the middle: 48.16% of the four star compartments in the registry still defrost manually, and manual defrosting means a day's work once or twice a year.
How to judge the seller. Ask whether delivery is to the floor and whether the old appliance is taken away. Then check that the listing states the exact model and not the family: on freezers the codes change by a single letter, and with it capacity and defrosting change too. Comparing the same code across several shops is still the fastest way to read the real price: on SniffaPrezzi the offers sit side by side, while the listings and availability of the models cited here are in the Freezers category on OpportunityCommerce.
Setting 18 below zero and leaving it there is ninety per cent of the job. The rest is not filling it past the rim of the drawers, writing the date on the packs, and remembering that the months printed on the box are a conditional promise. For running costs and for replacement the numbers are in how much a refrigerator consumes in a year and in how long a fridge really lasts; if instead it frosts up too quickly or will not come down to temperature, the checks to run before calling a technician are in fridge making noise or not cooling and in how often to defrost and clean the refrigerator.
Sources
European EPREL registry, refrigerating appliances group: 56,519 records downloaded on 27 October 2026, 55,271 unique by brand and model, 37,085 household appliances with at least one frozen food compartment, excluding wine storage appliances and low noise appliances.
Regulation (EU) 2019/2016: definitions of the 0, 1, 2, 3 and 4 star compartments, Annex IV table 3 for target temperatures, and the freezing capacity threshold of 4.5 kg per 24 hours per 100 litres.
Bosch user manual for built in freezers, Italian section: chapter 8 on super freezing, chapter 10 on freezing capacity and storage at 18 below zero, chapter 13 on power failure.
Product information sheet and technical sheet of the Bosch GIN81VEE0, for the declared storage time in case of power failure and freezing capacity.
Official Bosch website and its freezers section.
OpportunityCommerce catalogue and prices read on 27 October 2026: 157 entries in the Freezers category, 88 freezers net of accessories, 44 matched to their EPREL record.
