What is Isofix?

It's the safest way to transport a child, but what is Isofix?

BuyaCar team
Mar 24, 2021

The Isofix system is the easiest and safest way of installing a child seat in your car. It’s used internationally by vehicle and seat manufacturers, although it’s known as Latch in America.

Isofix attachments consist of metal hoops, connected to a car’s structure. Compatible child seats clip on to these, ensuring a secure attachment within seconds and - usually - a clear way of checking that your seat is correctly installed.

It’s a major improvement over the alternative, which involves using the car’s seatbelts to attach a car seat. Not only does this take longer, it’s also difficult to see whether it has been correctly installed. In fact, Britax, the car seat manufacturer, which co-developed the Isofix system, estimates that fewer than a third of child seats fitted using a seatbelt are correctly installed.

Most cars sold since 2006 have Isofix attachments fitted, even though it wasn’t until 2014 that all new cars sold in Europe we required to be equipped with at least two sets of Isofix points (except for two-seat cars).

Is Isofix safer?

The main safety benefit in using an Isofix seat is that it’s far more likely to be fitted properly. Britax’s widely-used research found that just 30% of child seats attached with a seatbelt were fitted correctly, compared with 96% of those using the Isofix system.

It’s unsurprising, as seatbelt-mounted seats can take several minutes to fit correctly. Some require strenuous effort to tension the seatbelt correctly and, in some cases, belts to be strapped to the seat in front.

In contrast, the Isofix system clicks into place within seconds and most seats have green and red indicators to clearly show when a seat is (or is not) securely in place.

As long as they are fitted correctly, a child seat fixed with Isofix or with a seatbelt will both provide high levels of safety for children, they both comply with European safety standards.

How does Isofix work?

The key part of the Isofix system are the two metal hoops, incorporated into the vehicle’s main structure or chassis, which can be found in the gap between the car seat back and cushion. Sometimes these are open, just behind the gap opening, but many manufacturers put them in a plastic housing with a lid that can be flipped open or removed.

There’s also a top tether behind the car seat, either at the rear of the seat back or on the floor.

Isofix child seats simply clip onto the metal hoops, which are a standard 28cm apart in every car. The hoops hold the seat securely in place, but some seats also require extra support. If so, they either have a strap, which runs behind the car seat and clips to the top tether; or a foot, which extends into the footwell and rests on the floor of the car.

Child seats that use a support foot can’t be placed over underfloor storage compartments, as the force of a crash could crack the lid and cause the seat to dangerously tip.

Isofix seats for babies and young children are often made up of two parts: the seat and a base. The base clicks into a car’s isofix mounts, and the seat is then fixed to the base - usually by clips within the base. This system makes it easier to remove the whole seat, when you don’t want to disturb a sleeping baby, for example.

Which cars have Isofix?

All new cars sold in Europe since 2014 must have at least two sets of Isofix points (assuming they more than have two seats). However, the system has been fitted to the vast majority of cars since 2006.

Not all child seats are compatible with Isofix, and some of the bulkier seats won’t fit in small cars, so it’s always worth checking that the seat and car are compatible before making a purchase.

Some cars have more than two sets of mounts (six in some cases) but these may all be in a row along the back seats. If that’s the case, and you want to use all three, then you may find that only extremely narrow seats will fit.

In some cases, manufacturers can retro-fit Isofix points to certain older cars that didn’t have them as standard. Given how critical this is to safety, it’s advised that this is done through an official dealership.

Is Isofix a legal requirement?

Child seat manufacturers are not currently required to include Isofix mounts with their seats, and so you can buy several that are fitted with seatbelts. Both types of seats must pass official safety tests.

New legislation, currently being introduced, will eventually outlaw the sale of new, non-Isofix child seats. Called i-Size, this regulation will require tougher crash tests and Isofix mounts. You can already find i-Size seats in shops and these will soon become the only type of child seats that you can buy.

European regulators have said that seatbelt-fitted child seats will remain legal to use even after they have been banned from sale.

What does Isofix mean?

The Isofix name is a combination of two elements. The first three letters come from the body that regulates the standard: the International Organisation for Standardisation. The second comes from the system itself, which “fixes” child seats in place.


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