How did the system get its name?

ISOFIX is a particularly safe and easy-to-use mounting system for children’s car seats, in which a solid connection is created between the car body and the seat. The system is standardised according to the ISO 13216 norm. This norm also gave rise to the name.

The international organisation for standardisation defined the ISO 13216 standard (ISOFIX mounting systems) for the first time in 1990 and made the system available for the three ECE groups 0, 0+ and I. In October 1995 the system received approval from the European Commission and the FIA (Fédération Internationale de l’Automobile). The FIA is the international umbrella organisation of all automobile clubs worldwide, in which for example ADAC or ÖAMTC represent their respective countries.

How does ISOFIX work?

In the car, the ISOFIX mounting system consists of two brackets that are connected to the chassis and that can be found in the gap between seat rest and seat. The children’s car seat is then hooked into these brackets.

In Europe only rigid connectors are permitted for use in child restraint systems. These connect to the car’s ISOFIX bracket by means of a click function. During installation an audible click must be heard to ensure a correct locking onto the brackets. This fixed system differentiates noticeably from the American latch system. The acronym “LATCH” stands for “Lower Anchors and Tether for CHildren”. In this system the children’s seat is attached to the mounting brackets of the car with tight belt straps.

Which ISOFIX systems are there?

  • ISOFIX platforms or base frames with p support to the vehicle floor (support bracket or prop).

Infant car seats can be installed facing forward or to the rear. CYBEX offers these systems (ATON Base-fix) with its rear-facing infant car seats ATON und ATON 2 in Group 0+. The new groundbreaking combination car seat SIRONA for categories 0+/ I, which ensures safe rear-facing transportation of small children from birth to 18 kg (around age 4) is fixed onto an ISOFIX platform, whose innovative construction also allows for a user-friendly 360-degree rotation. The automobile must be compatible with the platform. In order to ascertain compatibility one should consult the automobile list on the children’s seat manufacturer’s website.

  • ISOFIX Connect seats with integrated ISOFIX connectors for forward-facing usage.


CYBEX offers all its children’s car seats of the categories I/II/III (PALLAS series) and II/III (SOLUTION series) in both versions: with and without ISOFIX-Connect system. Only the specialised Group I children’s car seat JUNO-fix is available exclusively with the ISOFIX-Connect system, in order to ensure the best possible safety for this age Group. The so-called semi-universal installation (homologation depending on automobile type), the installation of the children’s seat with the ISOFIX-Connect system and 3-point seatbelt is only permitted for specific car models, which are listed in a list of compatible car models (compatibility check). These seats are, however, universally homologated for conventional installation with the car’s three-point seatbelt. In this case no compatibility check is necessary.

  • ISOFIX seats with universal homologation require the use of a top tether that restricts forward displacement

The top tether is connected to an anchor point in the automobile, usually located behind the seat rest. Generally only forward-facing group I seats with backrest are equipped with a top tether system. This system does have its weaknesses however, as practical tests and research has shown. Primarily, the complicated installation and the high potential for misuse with the resulting hazard potential should be mentioned. Current studies from various institutions in the USA have shown that only 17-30% of users installed the top tether correctly. In a shocking 70-83% of cases the top tether was either not used at all or used incorrectly. The top tether was either not taut enough or too taut, twisted or attached to the wrong anchor point of the car. A further problem is that only a few cars are equipped with top tether anchor points, or the points are very hard to access. In reaction to this issue, CYBEX does not fit their children’s seats with top tether.


What are the advantages of ISOFIX?

  • For ISOFIX platforms nearly all installation mistakes can be avoided as no the seat is no longer secured with the car’s three point belt.
  • Thanks to the rigid connection with the automobile chassis the children’s seat (and with it the child) takes part in the deceleration process of the car at an earlier stage. The braking phase is prolonged, resulting in reduced stress levels
  • Simple and fast installation and removal of children’s seat
  • The rigid connection is also an advantage when the seat is not occupied, but still being driven around. However, ISOFIX Connect seats (with integrated connectors) still have to be secured additionally with the three-point seat belt
  • For these reasons children’s seats with ISOFIX connection achieve better overall results in crash and safety tests than otherwise identical car seats that are secured with the car’s three-point belt only. That’s why safety experts and accident researchers recommend the ISOFIX system.


Are there drawbacks?

  • ISOFIX seats can usually only be installed on the outside seats on the back bench. However, the midsection of the rear bench is considered safer if equipped with a three-point seatbelt.
  • Before purchase it is necessary to verify whether or not the desired ISOFIX children’s seat is compatible with and approved for use in one’s own car.


You can find out more in our CYBEX Child safety centre: