R129 (i-Size) and R44/04 Car Seat Regulations


By law all children must travel in the car in a seat that is suitable for their weight, height and age.

There are two car seat regulations in Europe, ECE R129 which was introduced in 2013 and ECE R44 which has been around since the early 1980s (the current version is R44/04). R44 was discontinued in September 2023 and although you can continue to use any R44/04 seats that you already own, most manufacturers have now stopped making them.


There are a few differences between R129 and R44/04 car seats

  • - In an R129 car seat all children must rear face until they are at least 15 months old or 76cm tall, regardless of their weight. R44/04 allows forward facing from 9kg regardless of age.
    - R129 car seats have height limits, they don't have set weight groups like R44/04 ones do.
    - Advanced technology 'Q' crash test dummies have 32 sensors to simulate a child’s fragile body more accurately. The 'P' dummies used for R44/04 only have 4 sensors.
    - R129 car seats have all passed a side-impact test which is not compulsory in R44/04 testing.
    - I-Size child seats are guaranteed to fit in any i-Size approved vehicle. From 2016 onwards some, but not all, new cars have at least two i-Size compatible seats.

  • - R129 can seats can be no more than 44cm wide to increase the chance of being able to fit three seats across the back seat of the car. R44/04 seats have no width restrictions and can be as wide as 48cm.
    - In most R44/04 combination seats the belt is routed differently for rear and forward facing. R129 seats only have one belt path for both travel directions, to avoid confusion and prevent mistakes.
    - Belt fitted R44/04 seats have blue seat belt guides for rear facing seats, and red for forward facing. In R129 seats all belt guides are green.


    R129 car seats for older children come in four height categories

    - i-Size Infant carriers up to around 75-85cm (these limits vary, so please check your instruction manual to check your seat's limit)
    - i-Size seats up to 105cm, which is about four
    - Belt fitted or ISOfix seats up to 125cm, around six or seven years
    - i-Size high back boosters up to 150cm or twelve years

    Infant carriers and harnessed seats up to 105 and 125cm do still have a seat-specific weight limit which can be found on the orange sticker on the back of the seat, and this limit must not be exceeded.


    A few examples of R129 car seats

    Most infant seats have a base that can also be used for a bigger seat up to 105cm for older children.

    ECE R44/04 weight groups

      Group 0, from 0-10kg, birth to 9 months
      Group 0+ from 0-13kg, birth to 15 months 
      Group 1 from 9-18kg, 9 months to 4 years 
      Group 2 from 15-25kg, 3 to 7 years 
      Group 3 from 22-36kg, 6 to 12 years *


      * You should choose your child's car seat according to their height and weight, and use it up to its limits. All children are different and the age given is just a rough idea of how long you can expect a seat to last, based on an average 50th percentile child. Children only grow out of their car seat by weight or height, never by age.

      But the age at which they can start using a seat is important. The regulations' 9 and 15 months minimum forward facing ages are far too young. Regardless of how big or heavy they are, the bones in a child's neck and spine don't begin to fuse together until they are between two and three years old, and it takes about three years for this process to complete. So it isn't actually until they are six that their neck is strong enough to cope with the forces of a car crash. This is why it is important for children to travel rear facing for as long as possible.

      The same applies to the move from rear facing seat to high back booster. Although according to the regulations a child can go into a booster seat at 15kg or 100cm, a lot of children reach that weight or height long before they are physically strong, and mentally mature enough to sit in a booster seat. We recommend rear facing until 125cm, which on average is between six and seven.

      When this picture was taken in 2011, this 93rd percentile baby was six months old. He already weighed 9.5kg, so legally he was 'heavy enough' to face forward. A perfect example of the fact that legal doesn't necessarily mean safe... (This car seat was a combination one which he only used rear facing.)

      Combination car seats

      Apart from Group 0+ infant seats, most car seats cover more than one weight group. There are lots of different combination seats available, these are just a few examples.


      The orange sticker

      All car seats have an orange approval sticker, usually on the back. This sticker tells you whether the seat is an R44/04 or an R129 one, it gives the height and/or weight limits, and the seat's approval number. The circle with an E in it indicates that the seat is approved for use in Europe and the number is the country it was tested in. For example 1 is Germany, 4 is the Netherlands, 5 is Sweden, 11 is the UK, etc. Each country has its own number, but seats from any European country may be used in any other.

      It will say Universal meaning the seat will fit in most cars, or Semi-Universal if it has a support leg which you may not be able to use if your car has storage compartments in the footwell. The Y indicates that the seat has a harness with a crotch strap. Seats bought outside Europe which do not have this sticker are not legal in Europe and must not be used here.