The Good Egg Car Safety Blog

What is i-Size?


Over the past year or so, we have seen lots of advertisement for i-Size car seats.  But what exactly are they, and what is i-Size?

RF harness height


i-Size is…


    • A new regulation, called R129, within R129 is i-Size.


    • It will eventually replace R44.03 and R44.04 child car seats.


    • R129 was launched in 2013, and is proposed to be fully implemented by 2018.


    • It aims to keep children safer in the car, by making seats easier to choose, fit and use.


    • ISOFIX seats are being addressed first, then belt fitted seats will be addressed.


What are the key changes?


    1. New test dummy – the new crash test dummy, the Q dummy, can measure far more points of force than the old P series dummy. This will give more information as to how a seat can reduce the force a child is subject to in a collision. This information will allow safer seats to be made.




    1. Mandatory rear facing to 15 months – Under the R44 regulation, children can legally forward face when they weigh 9kg. Young children have very heavy heads and weak necks however, and it is very dangerous for them to face forwards.  The current R44 regulation could allow children to legally face forward before their neck is fully developed. i-Size seats require children to be rear facing to at least 15 months old, a point when a child’s neck is stronger and more able to cope with the forces applied during an impact when facing forward.


                15 RF OL

    1. Side impact test – you may be surprised to read that side impact testing isn't already mandatory. The R44 crash test doesn't legally require child car seats to undergo a side impact test, although many manufacturers test their seats to ensure they do protect in a side impact.  i-Size has taken this a step further and now legally requires car seats to provide side impact protection.

    1. Seats selected by height – child car seats are traditionally selected by a child’s weight, then height, with an age guideline. However a child’s weight is often unknown and the age guideline is used instead, which can mean the child may not be big enough to use the seat, even at the right age. i-Size seats change this to make seats selected by height, then age.  Weight limits will still be in place, however these will be specific to the child seat and clearly advertised.


                       height OL

    1. Better compatibility - i-Size seats address the problems of R44 ISOFIX seats not being compatible with all vehicles. New vehicles can now have an i-Size approved seating position, which an i-Size child seat will be automatically compatible with – no fitting list will need to be consulted. This is achieved by the vehicle manufacturers making the interior of the vehicle to approved specifications.  For the child seat to be approved for i-Size, its external geometry must fit within a set sized ‘envelope’ and the support leg must meet the specified geometry and adjustment.



    1. Child seats will be easier to use – The internal dimensions of an i-Size seat will be specified. The seat harness must allow a 95th percentile child to fit within it, the harness must be simple to adjust and the cover easy to remove.  The harness must be made so that it cannot be removed from the child seat to reduce misuse.


Are R44 seats still legal?

Yes, R44 seats are still legal to use, and you are not legally required to buy an i-Size seat.  In 2018 i-Size will be fully implemented, however you will be allowed to use R44 seats for some time after 2018 – the two regulations will run alongside each other for some years yet. (*please note, only R44.03, R44.04 and R129 seats are legal)

What about seats that don’t fit within i-Size?

Some seats will not fit within i-Size – such as larger extended rear facing seats.  These seats will still be able to achieve R129 approval, just not the specific i-Size approval.

Will booster cushions become illegal?

It is still unknown if booster cushions will be made illegal.  As R129 includes a side impact test, and booster cushions cannot pass a side impact test, it does look like they will not be able to gain the approval.  However, it may be that booster cushions will be for older children only, with the vehicle providing protection for the child.

Why is it rear facing to 15 months?

Young children are safer rear facing as their head is very heavy, and their neck very weak – this is not a good combination in a collision.  By rear facing for longer, the neck is protected.  The minimum age for rear facing is 15 months, however many i-Size seats currently available allow rear facing to 4 years old – 105cm.  The 15 month limit may increase in the future.

Can i-Size seats be used in cars that aren't suitable?

Yes, i-Size is backwards compatible and can be used on a cars standard ISOFIX.  However you will need to ensure that your vehicle is on the fitting list for the i-Size seat.

Will I need to buy new seats in 2018?

No, R44.04 seats will still be allowed to be used for some time after this point.

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Sunday, 23 July 2017

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