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Child seats of groups 2 and 3 and progressive seats: when to switch

Child seats of groups 2 and 3 and progressive seats: when to switch


If your child is outgrowing their first, small child seat, you may be searching for a Group 2 seat on the market, for children weighing from 15 to 25 kilograms. Although both weight and height must be referenced when assessing changing the child seat, these seats are valid for ages 3 to 7, approximately, for the highest percentile of cases.

However, it is noteworthy that for Group 2 child seats, individual seats of well-known brands practically do not exist in that group. Instead "Group 2 and 3" seats, also called "Group 2/3", may be found.

Description of Groups 2 and 3

  • Group 2: Indicated for children from 15 to 25 kilos. These are seats that use the vehicle's seat belt to restrain the child and have a cushion plus back support that fits into a passenger seat of the vehicle. In this way the child is raised for the vehicle's seat belt to properly restrain them.
  • Group 3: Indicated for children from 22 to 36 kilos. These are booster cushions, sometimes including a back support, though not necessarily, that raise the child for the vehicle's seat belt to properly restrain them. In Spain it is mandatory to use a child restraint system until the child exceeds 135 cm and its use is recommended for up to 150 cm. In other countries it is mandatory for up to 150 cm.

Progressive seats

The reason why Groups 2 and 3 are joined together is because child seats of both groups can have similar shapes and sizes. Therefore, with a progressive restraint system, with different positions that adapt to the child's size, both groups can be encompassed at once.

A "Group 2 and 3" seat shall be useful for children from 15 kilos and shall have variable adjustment to be used up to 36 kilos or when the child exceeds 135 cm, which is the minimum height to stop using a child restraint system. Specifically, a height-adjustable headrest is usually available to protect the head as the child grows. Seats certified as Group 2 and 3 include different designs and shapes, fixed or reclining, with more or less side protection and various price ranges.

Group 1, 2 and 3 seats

Recent advances in design resulted in several brands that offer progressive seats covering groups 1, 2 and 3. These seats have a harness to be used as Group 1. The harness, part of the stool and back support are subsequently dismounted to turn it into a Group 2 seat, with the adjustable-height headrest to turn into a Group 3 seat. This means that the same seat may be used from the time the child weighs 9 kilos until they exceed 36 kilos, or translated into age, from 1 to 12 years, approximately.

Beware not to transfer to Groups 2 and 3 too soon

It is advisable not to switch to a Group 2 and 3 seat if the child has just reached 15 kilos and is still comfortable in their Group 1 seat, especially if the latter is placed in a rearward-facing position. If the Group 1 seat harness it is still appropriate, following the installation instructions for the child seat, it will restrain the child more properly in case of an accident. Also, if placed in a rearward-facing position, it will restrain the head more properly in case of a head-on collision than a Group 2 and 3 seat.

There are children with very high percentiles that reach 15 kilos at an early age. If the Group 1 seat is too small, but the child is still too young, recently turning 3, for example, a Group 1 seat, slightly wider, may be more appropriate than going onto Groups 2 and 3. The reason is that a very young child is fidgety and moves around a lot if left loose. With a Group 2 and 3 seat, the child will have much freedom of movement and may even pass their torso under the seat belt, which would leave them unprotected in case of an accident. Therefore, it is important to move onto Group 2 and 3 at the appropriate time, when the child has gained awareness and has learned to keep calm in the vehicle.


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