What is ISOFIX and how does it work?

When buying a car seat for your new baby, which is essential as you won’t be able to take your baby home from the hospital without one, you’ll come across ISOFIX, but what exactly is it?

Many car seats on the market now are ISOFIX compatible, and from 2018 manufacturers will only be able to sell ISOFIX car seats, due to the new i-Size law.


i-size picture
i-Size logo

When buying an ISOFIX base, it is important to make sure you buy the correct base for your particular car seat, this might sound like an obvious thing to do, but there is such a wide choice and many of the brands have different bases for their range of car seats (just to make things more difficult).

What is ISOFIX?

ISOFIX is an internationally recognised system of allowing you to fit a car seat into your car, without having to use the cars seat belt. It’s only been widely used since 2006, as this was when a new law was passed stating that all new cars had to be fitted with ISOFIX fittings. If your car was made before 2006, it might not have these fittings, therefore you will not be able to use ISOFIX, but some brands do sell bases that can be fitted with a seat belt. Our Joie i-Anchor base can be fitted with both a seat belt and/or ISOFIX.

ISOFIX works by using metal anchor points built into the car’s chassis, on which the ISOFIX connectors from your car seat/base fix onto. Once the connectors are clicked into the anchorage points, a baby car seat has to have a third point of connecting to the car. This is either done by using a leg extending from the base which sits on the floor, or by a top tether which is a strap attached to a mount somewhere behind the rear seat. Both of these work to stop the car seat from tipping forward, in the event of an accident.

Most car seat/bases on the market have visual and/or audio indicators to help you ensure it is fitted correctly in the car. The indicators on our i-Anchor base turn from red to green when everything is fixed properly and securely. Very helpful!


When buying your ISOFIX base it is important to check that it will fit into your car, as not all ISOFIX bases fit into all cars. Most brands, like Joie have a checklist on their website where you can check which car seat will fit in your car. This helped us when looking for a new car seat for the little tester, as we had to make sure the base would fit into 2 different cars. Having an ISOFIX base installed, can make swapping a car seat from one car to another easier, as you won’t need to thread the seat belt through the guides.


Base fitted into the car.

One of the main reasons ISOFIX came into place was to make it easier for parents/carers to install their child’s car seats safely, every single time. Many people including retailers make errors when trying to install car seats, ISOFIX is designed to make installing car seats quicker and easier. It also helps to remove the potential of putting the car seat in the car incorrectly.

Some cars are easier to install ISOFIX bases into than others, for example, the connectors in a Nissan Juke (2016) are tightly tucked in-between the seat back and the base, meaning you have to go digging to find the anchor points. Look for the ISOFIX labels on your car’s seat back, as these are normally placed directly above where the anchorage points are.


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If you have a travel system, having a base in the car can make it easy to quickly transfer your car seat from the car, onto the pushchair chassis and back again. Having this system was so useful when the little tester was a young baby when we didn’t want to disturb him if he had fallen asleep in the car.


I hope this helps if you are a little confused about how ISOFIX works and what it is exactly designed to do.

Thank you for reading,

Alice x

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