The Guide To i-Size

The Guide To i-Size

What is i-Size?

‘i-Size’ (ECE R129) is the new European wide, standard regulation for child car seats, designed to increase safety and run alongside the current ECE R44/04 regulation. I-Size does not replace ECE R44/04, but does offer the most stringent safety performance.

i-Size is the name of the first phase of the new R129 legislation ensuring enhanced performance criteria for car seats for children from birth to 105cm (approx. 4 years) which are installed with ISOFIX. R129 was developed using the very latest research into child safety in cars and is therefore the future of car seat safety legislation, but will continue to run side-by-side with ECE R44/04 in the years to come.

How does i-Size make travel safer?

I-Size focuses on child’s height instead of weight making it easier to choose the right car seat. One of the biggest changes brought by i-Size is the extended length of time required for the initial rearward facing child seats. A baby will travel rearward facing up to a minimum of 15 months or 105cm approx. 4 years old.

Why do we need a new regulation?

I-Size was developed using the very latest research into child safety in cars. Latest figures from Good Egg Safety, one of the UK’s largest in-car safety campaigners, reveal that 71% of child car seats are either fitted incorrectly or are incompatible to the child or car.

The first child car seat regulation was introduced in the 1980’s and has been updated ever since. Cars have dramatically changed and improved over the years and so should our car seats! We now have a better understanding of what happens during a car accident so compatibility between car seats and vehicles always needs to improve.

The current regulation (ECE R44/04) which focuses on a child's weight, can confuse a parent in to moving their child to a forward facing car seat too early. Typically around nine months a child will prematurely move into a group 1 forward facing child car seat (9kg – 18kg), as many parents believe their child has outgrown their car seat, this is because the current regulation uses weight groups. Just because a child has reached the maximum weight for their group or their feet are stick out the bottom of the car seat doesn't necessarily mean their body is fully developed.

Children grow at different rates so deciding the right a car seat by age/weight can be difficult, if you have a smaller child they may look swallowed up by the seat or a larger child may look uncomfortable. The new regulation helps to avoid this premature switch by stipulating that rearward facing travel is mandatory for children up to 15 months old in i-Size car seats. The child’s length is a better scale to determine the fit in a car seat than weight or age, there is a lot of variation between the length of children and their age.

What makes i-Size safer?

Safety is always improving and i-Size is newer and up to date, but don't worry that doesn't mean that you need to throw out your current ECE R44/04 car seat. i-Size is simply another option when choosing to buy a car seat.

You will notice that a newborn baby's head is proportionally much larger and heavier than the rest of their body. A baby's head is 25% of their body weight and so they are much more vulnerable in an accident. If a baby travels in the car facing forwards, their relatively heavy head is unrestrained and in a collision their head will be thrown forward. This can cause serious neck and head injuries. Rear facing car seats protect the head and spread the impact over a greater area protecting the neck, head and vital organs.

Recent research proves that a baby’s neck is not yet strong enough to support a baby’s heavy head until at least 15 months. I-Size requires rearward-facing travel to a minimum of 15 months to ensure the child’s neck has developed the strength needed to support an average forward collision. That’s why the new i-Size regulation is clearly stating that parents should use a rearward-facing i-Size car seat until baby is at least 15 months of age.

Better Installation

I-Size promotes Isofix and it is much harder to install an i-Size car seat incorrectly as they don't rely on a seat belt installation. I-Size car seats use the Isofix system which simply clicks onto your car's Isofix anchor points behind the car seat. Isofix is simple, quick and the safest method of correct installation of a child car seat in your car.

I-Size can be used in most cars that have Isofix fittings, which have been standard in the majority of cars since 2007 and mandatory since 2011.

Most child seat manufactures have a list that shows which seats are approved for which car models, as not every seat can fit every car!

Old vs. New, What’s The Difference?

i-Size will keep a young child rearward-facing for at least 15 months in stead of the usual 9 to 12 months. You choose a car seat you want based on a baby's length rather than weight just like clothing sizes.

The key differences are increased support for the child's head and neck and better protection in the event of both frontal and side-impact. The seat's five-point harness ensures that the child stays in the seat even in a roll-over accident.

Another difference is the current standard does not include side-impact testing, even though crashes can happen from all angles. Injuries from a side impact can be very severe to the child’s head, so for the first time ever in a child car seat regulation, it includes a set of minimum performance criteria for this type of collision. i-Size car seats will give a much better performance in-case of this type of accident.

And finally you can only install an i-Size car with the Isofix system previously mentioned.

What will happen in the future?

I-Size was introduced in July 2013 and is currently running alongside the current ECE R44/04 regulation but at some point in the future it will replace it.

The i-Size regulation does not replace the current ECE R44/04 regulation, so you do not need to upgrade your existing child car seat. If you are currently use a rearward facing child car seat that is fixed to the car by the seat belt, you can happily continue to use it. The introduction of i-Size simply means that you now have an extra option when buying a car seat for your baby/toddler – an option that complies to the new i-Size safety regulation.

Currently The first phase of R129 (i-Size) covers children from birth up to 105cm, approx. 4 years old. The next phase (R129) for ages 4 - 11 is in development – so keep your eyes peeled!

Introducing The Maxi-Cosi AxissFix i-Size Car Seat!

The new AxissFix car seat from Maxi-Cosi is compliant with the latest i-Size legislation, suitable from 61 cm to 105 cm (4 months - 4 years approx.)


Maxi-Cosi AxissFix offers safer rear-facing travel up to 87 cm (approx. 2 years) to increase head and neck protection for your child in the event of an accident. The AxissFix can be easily rotated from a rearward to forward facing position when a parent feels their child is of a correct height to move forward to the next car seat stage. If you are unsure, a measuring height indicator helps you to know when it's time to switch from rearward to forward facing!

For parents convenience the AxissFix is easy to install securely using a Top Tether and IsoFix connectors that lock the car seat to the body of the car. Colour indicators confirm that the seat is correctly installed giving parents complete peace of mind.

With a 360° swivelling seat there's no need to lean over, squeeze and struggle trying to place your baby in the car. The AxissFix allows you to turn the seat to face you for front on access and then simply rotate the seat to either rearward or forward facing.

This i-Size car seat features four recline position in both directions and a comfy padded seat that can be rotated in every sitting position. Featuring harness hooks and one-pull harness system, you can secure your little one in seconds. The harness and headrest can be adjusted simultaneously to suit the height of your growing child.

Your child's safety is the highest importance, the headrest has high performance absorption material for extra protection in case of side impact and the 5-point safety harness has anti-slip harness pads for high restraint performance in case of frontal impact.

For queries please use the online chat service or email our friendly customer care team. Pop into store to speak to a trained car seat fitter to ensure compatibility before your purchase.

Introducing the 2wayFamily...

Discover the Pebble Plus, the latest edition to the Maxi-Cosi i-Size family. This is an i-Size baby infant carrier that embraces your baby offering excellent safety and extra comfort.

Pebble Plus

Suitable from birth to 75 cm (approx. 1 year), this i-Size car seat is part of the Maxi-Cosi 2wayFamily collection offering up to 4 years of rearward facing travel and improved head and neck protection for your child in the event of an accident.

This infant car seat includes a comfortable baby-hugg inlay for a better fit and lying position for a new-born, alongside impact-absorbing material at the top side wings, this provides even extra protection from side impact collisions.

To meet the i-Size standard we recommend using this car seat with the 2wayFix Base (available at Direct2Mum), providing the safest Isofix installation and a highly convenient click-and-go system.

Meet the safest toddler car seat in the Maxi-Cosi portfolio, the 2wayPearl! Offering extended rearward facing travel for children up to 105cm or approximately 4 years of age, the 2wayPearl is Maxi-Cosi’s first i-Size compliant car seat.


Maxi-Cosi 2wayPearl can also be used in a forward facing position any time from 15 months onwards if desired. It can be easily changed at the press of a button, allowing parents the flexibility to make the choice at which stage their toddler is moved to a forward facing position.

Offering full recline options in both positions for sleepy toddlers, this is one of Maxi-Cosi's most flexible car seats. Compact, safe and stylish, the 2wayPearl toddler seat will fit in almost every car with ease. The headrest and harness simultaneously adjust together to grow with your child so you never have to re-thread. The innovative easy-in harness stays open to easily get child in and out in seconds.

The 2wayPearl car seat is i-Size compliant and MUST be installed with the Maxi-Cosi 2wayFix base (available at Direct2Mum) using the Isofix attachments points to ensure a safe and secure installation in your vehicle.

Please visit us in store to place an order for the Pebble Plus or 2wayPearl and have one of our lovely trained store staff fit your car seat for you!

What is i-Size

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