ISOFIX – for the safe, simplistic and intuitive installation of child car seats

all you need to know about isofix

We give you all you need to know about ISOFIX – for the safe, simplistic and intuitive installation of child car seats.

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When you’re having a baby, your world is turned upside down. This time is special and of course exciting but also brings to mind a lot of new questions. One of which is how to identify the child car seat that suits your needs and your car best. Keeping your child safe on the road is also Britax Römer’s top priority. With more than 50 years of experience in child safety, Britax Römer has been involved in many ground-breaking safety innovations during this time. One of the most significant is the co-creation and introduction of ISOFIX.

Before ISOFIX was introduced installing a child car seat correctly had been a challenge. Since every car is different and so is every vehicle seat belt, 70%* of all child car seats had been installed incorrectly back in 1995. To reduce this number, a development group including child car seat and vehicle manufacturers worked on bringing a simple and intuitive installation concept to life. But it was Britax Römer who introduced the first car seat with ISOFIX in collaboration with Volkswagen at the IAA (International Motor Show) in 1997. This installation system is the one which is uniformly used on the market today and which is now an integral part of the new EU regulation for car seats (ECE R129 / i-Size).

all you need to know about ISOFIXBut what is ISOFIX and how is this an improvement? ISOFIX anchorage points in cars are standardised allowing any European ISOFIX compatible child car seat to be connected to them. It is mandatory for all new cars to be equipped with ISOFIX anchorage points since February 2013 and ISOFIX car seats are now compatible with a large number of vehicles.


The ISOFIX connectors on the car seat latch onto two metal anchorage loops situated between the back and bottom cushion of the vehicle seat. That way ISOFIX optimises protection through a strong connection to the car chassis and makes installation intuitive and easy. So every time you, a grandparent or friend, have to fit the car seat into your car or into another car, room for error during the installation is significantly reduced.

In the most common crash situations, frontal collisions, the child car seat is accelerated forwards. ISOFIX keeps the seat well connected to the ISOFIX anchorage points at the base of the seat. In order to avoid the seat rotating forward in such an event, it needs to have a second attachment point, such as being held back on top by a ‘Top Tether’ or being supported in front by a support leg.

all you need to know about ISOFIXA support leg stabilises the car seat or infant carrier base via the vehicle floor. It minimises the tilting and rotational movement and reduces the forward movement forces exerted on your child in the event of a collision. Child car seats with ISOFIX and support leg mostly take up more space in the footwell of the car and they are generally not suitable for cars with floorboxes under the footwell. For those child car seats you can simply check with Britax Römer’s FIT FINDER® on their website if your child car seat is compatible with your vehicle.

all you need to know about isofixA ‘Top Tether’ on the other hand is a strap which attaches the top of the child car seat to an additional anchorage point behind the back seat of the vehicle, in the boot or on the roof, normally marked by a small anchor symbol. At Britax Römer, all Top Tethers have a V-shaped form that used two anchorage points on the car seat for even greater stability and safety for your child when compared to single tether designs, which are most common in the market. The benefit of ‘Top Tethers’ over support legs is not only less space needed in the footwell of the car but also the fact that you can install the car seat in most cars with ISOFIX and Top Tether anchorage points.

Read our review of the Britax Römer Trifix here

Not sure if your car is equipped with ISOFIX? A quick look into the vehicle manufacturer handbook will answer this question. To make sure that your favourite child car seat fits in your vehicle, Britax Römer recommends a test installation at your local retailer before you buy your child car seat. Just ask for a member of staff trained by Britax Römer.

Read our review of the Britax Römer Advansafix III SICT here

For more on ISOFIX, why not watch Britax Römer’s ‘What is ISOFIX? The kids explain’ video on their Youtube channel here:

*GDV (1995)
*Gesamtverband der Deutschen Versicherunswirtschaft, association of German insurance industry


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