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Types of seats

Types of seats

There are various types of child car seats depending on the weight of the baby or child:

GROUP WEIGHT (key criteria) APPROXIMATE AGE (not to be used in the choice of seats)
Group 0 Up to 10 kg Up to approx. 9 months
Group 0+ Up to 13 kg Up to approx. 15 months
Group I From 9 to 18 kg From approx. 8 months to 3 o 4 years
Group II From 15 to 25 kg Approx. from 3 to 7 years
Group III From 22 to 36 kg Approx. from 6 to 12 years

Weight is much more important than age, as the weight determines the resistance afforded by child the seat, having said this, height too is important and the seats should never be too short or too small.

Height is another determining factor, and is even more important than weight. All child restraint systems officially certified under the ‘i-Size’ standard use the height factor to determine the correct child seat. 

At present, there are child seats for very small children: from 40 to 85 cm and from 45 to 105 cm.

In the coming years, as and when the next phases go into effect, the number of child seats that adhere only to the height guideline will gradually increase.

Following is a more detail description of each type of seat:

GROUP 0 ó 0+

Suitable for babies between 0 and 10 kilos (normally up to about 9 to 12 months of age, although age is an important guideline, more important is the weight), those in group 0; and for babies up to 13kg (normally up to 12 to 15 months of age, once again age is important but weight is much more so), and also those in in group 0+. Taking into account the ‘i-Size' standard, you will find child seats for children of 40 to 85 cm (up to around one year old) and from 45 to 105 cm (between six months and four years old, approximately)


The seats in this group can be two types, firstly carrycots or baskets and secondly child seats. The carrycots and baskets that are classed as baby carriers are less usual although equally approved for use in vehicles (read the instruction book to ensure they are approved for use) The baby travels lying down in a natural position but in some cases this type of seat can only be used with the seatbelt over the tummy which means that in a lateral collision the baby is not so anchored (although there are now seats equipped with harnesses in a “Y” shape which improve protection in a lateral collision).

The baby seats are the most common type. They are often referred to by their commercial name of “maxi-cosi” (In reality this is the brand name of a producer of seats and infant products). Baby seats must always be installed facing backwards 

  • IMPORTANT: The baby seat should always be forward facing 
  • NEVER backwards. In a vehicle equipped with a front airbag it must have been deactivated. 


For children from 9 to 18 kilos (normally between 1 and 3 years of age, although age is an important guideline, more important is the weight)


Consisting of seats fixed to the vehicle using the car seatbelt or with the ISOFIX system and with the child restrained by a safety harness facing forward (the most common) or facing backwards which is more usual in Nordic countries.

  • IMPORTANT NOTE: in a very young child the weight of the head relative to the body is much greater than that of an adult. Also the neck is not fully formed. It is therefore recommended to always use where possible (never using a seat that is too small) a backward facing system. 


From 15 to 25 kilos (normally between 3 and 6 years of age, although age is an important guideline, more important is the weight) 

Consisting of a cushion and a backrest positioned on the seat of the vehicle on which the child sits and is fastened in using the seatbelt. This type of “booster” seat lifts the child to a level where the seatbelt can be properly adjusted, passing over the most resistant parts of the body of the child (the hips, sternum and collar bone).


From 22 to 36 kilos (Normally between 6 and 12 years of age, although age is an important guideline, more important is the weight)


This consists of a booster cushion, in some cases with a backrest, which is normally placed on top of the car seat. As in the previous group, the child sits on the booster cushion and is secured with the vehicle's seat belt. This kind of child seat "lifts" the occupant so the car's seat belt can be adjusted correctly to the child's body, resting across the most resistant parts of the body (the hips, chest bone and collarbone).

The forthcoming regulatory changes will require the use of a booster seat or cushion with a backrest (only in respect of the certification process of these CRS).

It is worth remembering that some seat models can be used for various weight groups. Consequently, it is common to find seats in groups 0/I (which can be used from birth up to when the child reaches a weight of 18 kilos), or in groups II/III (from 15 to 36 kilos). As and when a seat covers more weight groups, it becomes increasingly difficult to guarantee the same level of safety for everyone; for this reason, the usual case is that many of the seats that are only addressed at a single weight group are the safest ones. Parents therefore need to decide (and this often goes hand-in-hand with their financial situation) whether to buy a seat for each growth phase or one that covers various phases.

RESULT OF STAGE:  Having arrived at this point you should have decided which type of seat you need. You can then move on to the next stage: Choosing the most suitable seat (which type? which is best?).

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