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i-Size car seat regulations come into force

New i-Size and R129 must-know for parents


i-Size approved seats will keep babies rear facing until 15 months old

The government has just updated its law on child car seats. But the new i-Size regulations are proving to be confusing. Here’s what you need to know about buying child car seats from now on:

All car seats must pass certain tests before they can go on sale. The new European standard for child car seats, known as i-Size, forms part of new regulation ECE R129. 

The R129 – aka i-Size – regulation makes it mandatory for babies to stay rear facing until they are 15 months old. It will also change the way parents buy a new car seat – based on a child’s height rather than the current weight groups.

1) Do I need to rush out buy a new car seat? 

No. The current R44.04 car seat regulation will run alongside R129 for a while yet. R44.04 will eventually be phased out, but this is not expected to happen for several years.

If you currently have a car seat approved to R44.04 regulations (you can check by looking for those letters and numbers on the seat or on its label) you do not need to buy a new car seat and can continue to use the one you have.  

Joie i Anchor i-size approved seat

Joie (pictured) Maxi-Cosi and Concord all produce i-Size approved car seats

i-Size car seats cannot be attached to a car using a seat belt, so if you do not have ISOfix points in your car (maybe because it’s an older model) then you won’t be able to use a new style i-Size car seat with your current car anyway. But you will still be able to buy car seats approved under both regulations, so don’t panic, you won’t need to replace your car either.

Looking for a car seat that’s performed well in our Which? independent safety tests? Browse our car seats Best Buys.

2) How does i-Size make travelling with a baby safer?

i-Size makes travelling with a baby safer in three ways:

  1. Child car seats will be easier to fit.
  2. i-Size provides better protection from side impacts.
  3. i-Size makes it mandatory for babies to stay rearward facing until they are 15 months old, which is safer in the event of a collision.

Learn about more key differences with i-Size car seats.

3) How do I know my child is ready to move to the next size child car seat?

i-Size seats are based your child’s height rather than weight. As parents are deemed to know their child’s height better than their weight, it should make it easier to work out if the seat is suitable for your child and when he or she is ready to move into a larger seat. Your child will outgrow the seat once he or she exceeds the maximum height stated on that car seat’s label.

4) Why is rearward facing in a car seat for longer, safer? 

Babies and children are not mini adults, their bones and skeletons are different and need much more protection from the forces in a crash. 

Swapping your baby to forward facing when he or she is as young as nine-months or 9kg exposes your baby to more danger in the event of a front impact car crash. Because a baby’s head is bigger in proportion to the rest of their body, when the head is thrown forward through the force of the crash, there is more of a risk of spinal and neck injuries.   

It’s safest to keep babies in their rearward-facing infant carrier for as long as possible. Don’t be tempted to swap your baby forward-facing until he or she has:

  • Reached 15 months of age, or
  • Reached the weight limit for their current seat, or 
  • The crown of their head is level with the top of the car seat (which means it won’t be protected in a crash)

Keeping your baby in their infant carrier for as long as possible also saves money as it means you don’t need to buy a new car seat right now. 

See where Which? testing goes beyond the current UK standard for car seats in How we test car seats.

5) How does i-Size make fitting car seats easier?

The idea behind i-Size is that in the future all car seats will fit in all cars. Anyone buying a car or a car seat will, eventually, just need to look for the i-Size logo on both the car and the car seat. All i-Size car seats use ISOfix, a fitting system that attaches car seats directly to the frame of your car using connectors. Your car must also have ISOfix. Generally, ISOfix car seats are more simple to fit than car seats that use the vehicle’s seat belt.

Find out what is ISOfix?

The downside, at the moment, is that there are still only a very small number of i-Size approved cars available to buy. So you’ll need to check with your car’s manufacturer before buying an i-Size car seat. 

If you’re buying a new child car seat (whatever the make, model or regulation) we’d recommend you get it fitted by an expert. 

Download our free 10 child car seat fitting checks and make sure your child’s car seat is as safe as possible.

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