What is ISOFIX and how does it work?

ISOFIX is a quick and convenient way of getting your child car safety seat locked in place, but how does it work and does it make your kids safer?

ISOFIX is the handiest, and potentially the safest, way to securely put your child’s safety seat into your car. The whole idea is that instead of wrestling with seatbelts and straps, you simply click the seat into place, effectively anchoring it to the car’s structure. This guide will tell you how it works, and how much safer it is for you and your child.

What is ISOFIX?

ISOFIX is simply a series of metal clamps, which are attached to the back of a child car safety seat. These clamps are designed to a common global standard so that they match up with
anchoring points built into the seats of your car.

How does ISOFIX work?

Have a look at the back of an ISOFIX seat. There you will see two long metal arms, with self-latching catches at the end. These will often be painted a brighter colour than the rest of the seat. These are the child car seat’s anchoring points.

Now, look at the seats of your car. You will find ISOFIX points most commonly in the outer two rear seats of your car, and depending on the make and model, sometimes also in the front passenger seat. Look for a symbol of a child in a car seat, and that’s where you’ll find the ISOFIX anchoring points. Sometimes those anchor points will be just under the rear edge of the seat cushion, below the backrest. In other models, they will be behind protective plastic covers, which have to be removed or flipped up out of the way. In some cars, the ISOFIX anchor points will be behind small zipped-up fabric panels which need to be opened.

To attach the child seat to the ISOFIX anchor points, simply place the base of the child seat onto the seat of the car, with the two rear-facing arms aimed at the anchor points. Now, slide the seat backwards until the prong latch onto the anchor points, which should happen automatically. You may need a couple of tries, and a firm movement of the child seat, to activate the latching of the arms. Pull the child seat sharply forwards to check that the latch is secure.

To release the child seat from the anchor points, there will usually be a small release button for the arms, which you just need to squeeze to open the latches.

There’s also a third point of contact for an ISOFIX seat, usually called the top tether. This can be either an adjustable solid supporting leg, which comes from the forward edge of the child seat and which must be placed firmly in contact with the floor of the car, or a seatbelt-style strip of fabric webbing, which must be hooked onto a connecting point on the back of your car’s seat, or on the floor of the boot, or sometimes in the roof of the vehicle. You’ll need to check your car’s owners’ manual to find out precisely which is right for you. These top tethers or supporting legs prevent excess movement of the child seat in the event of a crash, and help to keep your kids safe. Not all ISOFIX seats will have a top tether or support leg, but most will.

Once all of this has been fitted, the ISOFIX child seat’s own internal harness will become your child’s seatbelt, maximising their safety until they’re big enough to use the car’s own seatbelt with a booster cushion. ISOFIX child seats come in both forward facing and rear facing designs.

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What are the benefits of ISOFIX?

• Accurate attachment: The biggest benefit of ISOFIX is that it’s simple and only works one way, meaning that you’re less likely to have an incorrectly installed child safety seat, which could be as dangerous to your kids as not having one at all. ISOFIX takes most of the uncertainty out of fitting a child safety seat.
• Fixed to the car’s structure: An ISOFIX seat, when fitted properly, is essentially part of the car’s structure, and anchored securely to one of the strongest points of the car. That means that an ISOFIX seat is much less likely to move around in the event of a crash than one that’s just secured using the car’s own seatbelts, and this again improves the safety for your kids.
• Quick and easy: While it can take a bit of time to get used to how ISOFIX works, once you’ve mastered it fitting a child seat to your car takes mere seconds. It’s also much less time consuming, and often easier on your back, than fitting a seat which requires running the car’s seatbelt through a series of clips and latches.

Is ISOFIX safer than a seatbelt?

Yes, ISOFIX is safer than using a seatbelt for two main reasons:

First, there remains the potential for a seatbelt to not be properly looped around the securing points on a child seat. ISOFIX massively reduces the risk of an improperly installed child seat, as the arms that lock into the anchor hooks give a veritable ‘click’ when secured, while a green indicator will also often show on the ISOFIX seat when it is securely attached.

Second, there is no slack in a seatbelt securing the seat to the car to be overcome in the event of a collision, improving safety further by reducing seat movement.

Types of ISOFIX car seats

Not all ISOFIX car seats are the same, and there are three main types, which conform to European safety standards R44-04 or R44-03. You can check which type your seat is by looking for a bright orange label on the side or underneath of the seat. The three main types are:

Universal approval

This is an ISOFIX seat which has been approved for use in any car with ISOFIX anchor points, and which should fit neatly into any car, although it’s always worth checking before you buy that your chosen seat works well with your car.

Semi-universal approval

As the name suggests, a semi-universals ISOFIX seat is designed to work with most cars, but it may not work with your specific car. Again, checking any seat you’re thinking of buying to make sure it fits your car and works with the ISOFIX anchor points is vital, and staff in shops such as Halfords will be able to help you with this.

Vehicle-specific approval

As above, the clue here is in the name – a vehicle-specific ISOFIX seat has been designed to work with one specific make or model of car, and will usually be a part of that car maker’s official accessories catalogue. Don’t buy one of these seats if you don’t have the car to go with it.

Does my car have ISOFIX?

Almost certainly: it has been a legal requirement to fit ISOFIX points in all cars with four or more seats sold from new since 2014, while all brand-new models launched to the market had to have ISOFIX by 2012. Many car makers were fitting ISOFIX points well ahead of these dates, though.

If you’re looking at second-hand cars ISOFIX should be listed in the vehicle’s specifications, or you can look out either for the two anchor points in photos of the car, or the ISOFIX logo, which is a stylised image of a child in a car seat.

The ISOFIX system is called LATCH, Canfix, LUAS or UCSSS in markets outside Europe.

What’s the difference between ISOFIX and ISOFIT?

Just to make things slightly more confusing, there’s also a system called ISOFIT (emphasis ours). The anchor points on an ISOFIT seat are identical to those on an ISOFIX one, but while an ISOFIX seat will have its own five-point built-in seatbelt that secures the child to the child seat, an ISOFIT seat secures to the car using the same points, but sees the car’s seatbelt secure the child to the car seat. ISOFIT seats tend to be for older children – for example a high-back booster seat is more likely to use the ISOFIT system.

How to fit and remove an ISOFIX car seat

While the process for fitting and removing an ISOFIX seat varies slightly from car to car and seat to seat, and instructions both for the car and the child seat should be closely consulted, in broad terms the steps for fitting an ISOFIX seat are as follows:

1. Locate the ISOFIX anchor points in the car; this may require removing a cover, or sticking your hand down between the seat backrest and squab.
2. Extend the ISOFIX arms from the child seat, and ready the support leg or top-tether strap, if applicable.
3. Insert the anchor arms so they attach securely to the anchor points. You should hear and feel a positive ‘click’, and a green light or icon may show on the child seat.ISOFIX bars tend to extend out quite far to allow them to
4. fit cars with longer seat squabs. Retract the ISOFIX bars back into the seat base until the back of the child seat meets the car’s backrest.
5. Secure the top tether or support leg, if the seat has one.
6. Put any ISOFIX cover in a safe place for future use.

Some ISOFIX seats come with inserts that slot between the car’s seat-back and squab; this can be useful if the car’s ISOFIX anchor points are buried between the base and back of the seats, as the inserts will effectively open a gap through which the ISOFIX arms can slide, saving you from having to wiggle the arms through a tight gap every time you fit or remove a seat.The yellow loops are the car’s ISOFIX anchor points; the purple arms are the child-seat latches; the blue insert is not found on all seats, but is a guide to ease fitting and refitting.

Here’s the process for removing an ISOFIX seat:

1. Loosen and detach the top tether, or take the tension out of the support leg, is using.
2. Activate the release buttons on both anchor arms simultaneously; this can be fiddly, but gets easier as you become familiar with the seat.
3. Remove the seat from the car, and replace any covers the vehicle’s ISOFIX points have.

What ages are ISOFIX car seats suitable for?

ISOFIX is a securing mechanism, rather than being a type of seat, so ISOFIX seats are available for children until they’re old enough to use just an adult seatbelt; this, by law, is once they turn 12 years old or grow to 135cm in height.

Our in-depth guide to child-seat laws has more information, but in broad terms there are five seat groups:

• Group 0 covers lie-flat baby carriers for infants weighing up to 10kg
• Group 0+ comprises rear-facing baby carriers for infants weighing up to 13kg
• Group 1 covers rear or forward-facing seats for children weighing 9-18kg
• Group 2 covers rear or forward-facing seats, and high-backed booster seats, for children weighing 15-25kg
• Group 3 covers rear or forward-facing seats, and high-backed booster seats, for children weighing 22-36kg

Concurrently, there is a system called ‘i-Size’, which sees seats grouped according to a child’s height. All i-Size seats come with ISOFIX points.

ISOFIX car seat FAQs

Is ISOFIX really necessary?

Strictly speaking no – there are plenty of child car seats which attach using the car’s own seatbelts as the anchoring points, and these provide adequate safety. However, it’s all too easy to make a mistake when fitting a child seat with the car’s seatbelts, and if the seat is out of the correct position or attached incorrectly, it’s simply not safe. ISOFIX takes that concern away, as the system only works one way, so once the child seat is latched in, you know it’s correct and safe.

What year was ISOFIX put in cars?

ISOFIX was, surprise, surprise, originally developed in Sweden in response to calls from the United Nations for a global safety standard for child car seats. The first production car to come with ISOFIX points was the Volkswagen Golf, in 1997, when VW collaborated with child safety seat maker ROEMER. In 2012, European legislation was introduced which made ISOFIX mandatory for all newly-launched cars from that point, and in 2014 a second round of legislation meant that all new cars on sale had to come with ISOFIX.

Do all child seats have ISOFIX?

No, ISOFIX seats are very much available from all good child seat retailers, but not all child seats use the system, so check carefully before you buy to make sure you’re getting what you need.

Is ISOFIX a legal requirement in the UK?

No, there’s no legal requirement that you have to use an ISOFIX seat, you’re free to choose which child safety seat best meets your needs, although it’s important to remember that you can be fined and given penalty points if your child’s seat is incorrectly installed, or of the wrong type for their size and age. ISOFIX takes away at least some of that worry. ISOFIX anchor points have been a legal requirement for all new cars since 2014.

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