Child Car Seats

i-size Seats

'i-size' is a new EU safety regulation for child car seats (ECE R129). It was introduced in July 2013 to make child car seats easier to fit, provide better protection from side impacts and keep children rearward-facing for longer. i-size only applies to Isofix seats. UK legislation has been amended to allow i-size seats to be used.

R129 and R44 run side by side, so parents can choose whether to buy and use child car seats that meet R44.04 or R129 (i-size seats). You do not need to swap your current seat(s) for i-size ones, unless you wish to do so. At some point (no date has been set) the law will probably only allow R129 seats to be sold, but even then parents will still be allowed to use their existing R44 seats for some time (probably a few years) afterwards.

The main changes that i-size introduces are:

  • i-size seats are based on the child's height rather than weight
    i-size uses the child's height to determine if the seat fits the child, rather than their weight. So, it's important to check that your child's height is within the range of the seat. Parents tend to know their child's height better than their weight, which should make it easier for parents to judge if the seat is suitable for their child and when they should move the child into a larger seat.
  • i-size rearward-facing restraints are for babies up to 15 months old
    Babies in i-size car seats stay rearward-facing until they are at least 15 months old. Currently, parents often move their baby to a forward-facing seat too soon.
  • side impact test
    i-size includes a side impact test to ensure that the seats provide better protection from side impact collisions.


Forward-facing i-size seats will be introduced in the future.

i-size child car seats fit in cars that have Isofix fitting points, but you still need to check if the seat is approved for your car. Contact your car manufacturer and/or the child seat manufacturer; many have a list on their website that shows which seats are approved for which cars.

i-size ready cars

i-size seats will fit any i-size approved vehicle. However, there are few such cars currently available in the UK. Their numbers will increase over the coming years.