What is iSize?

Children must normally use a child car seat until they’re 12 years old or 135cm tall.

Current groups of child car seat under ECE R44.04

Type of seatWeight     Group         
Rear-facing baby seatsBabies up to 13kg0/0+
Forward or rear-facing baby seatsChildren from 9 to 18kg 1
Forward-facing child car seats (booster seats)Children from 15 to 25kg 2/3
Booster cushionsChildren over 22kg 3

Only EU-approved child car seats can be used in the UK. These have a label showing a capital ‘E’ in a circle.

The current regualtion is ECE R44.04 which has been in place since September 2006 and is still current. New regulations however were passed in July 2013 called i-size and will eventually replace the older ECE R44.04 regulations.

Why i-Size?

i-Size regulations have been brought in as a new EU standard for increased child safety. To pass the i-Size test a car seat must pass a more stringent crash test and also a new test for side impact crashes. This will lead to safer car seats for your child.

The new i-Size regulation also provides longer rear facing for your child and car seats which pass i-Size will allow rear facing to a minimum of 15 months and in most cases far beyond. At Groovystyle we believe you should keep your child rear facing for as long as possible. Rear facing has been proven to be 5 times safer in a forward impact crash.

What is i-Size?

i-Size is a new standard for increased safety. It will lead to improved protection at higher forces for side and front impacts and a much better protection of the child’s head and neck areas. Rearward facing travel will be mandatory up to a minimum of 15 months and beyond in some cases. i-Size also promotes ISOFIX. i-Size legislation will be effective in addition to the current legislation ECE R44.

i-Size consists of:

  • Improved protection at higher forces for side & front impact and better protection of head and neck
  • Rearward faced travelling mandatory up to 15 months
  • i-Size promotes ISOFIX with use of top tether or support leg
  • i-Size car seats will fit all i-Size cars and almost all cars with ISOFIX
  • Length classification for easier choosing the right car seat 


Key points of i-Size

  1. i-Size seats keep the child rearward facing for longer - until the child is at least 15 months old. This offers greater protection for the child’s head, neck and vital organs.
  2. i-Size is based on the child’s height, rather than their weight, which makes it easier for adults to know they are using the correct seat for the child they are carrying. This is because height is more directly linked to physical development.
  3. i-Size seats will fit into ISOFix points, reducing the chance of fitting it wrong in the car. In the future, i-Size car seats will fit all ‘i-Size ready’ vehicles.
  4. i-Size seats will be tested more rigourously and this will lead to seats providing better protection of the child’s head, especially for younger children. 
  5. i-Size seats for young babies will also offer a significant improvement in protection for the head and neck.