If my child is over 135cm but under 12, do they still need a car seat in the UK?

Is the UK test age or height?

GOV.UK child car seat rules open with one sentence: children must normally use a child car seat until they are 12 years old or 135 centimetres tall, whichever comes first. Children over 12 or more than 135cm tall must wear a seat belt. The seat belts law page repeats the same pairing for anyone you are driving.

My child is over 135cm but still in primary school — do they need a seat?

Not as a matter of the main rule. If they have already reached 135cm, the height limb has come first, even if they are 8, 9 or 10. GOV.UK then requires an adult seat belt, not a child car seat. Measure standing height against a proper mark; do not use shoe size, age charts or 'they look tall in the photo'.

The child-seat duty and the belt duty are separate. A tall eight-year-old who has left the booster still has to wear the adult belt in a seat that has one. The driver remains the person GOV.UK holds to account until the passenger is 14.

What if they have turned 12 but are still under 135cm?

Age can come first too. A child who has had their 12th birthday may use an adult seat belt even if they are still under 135cm. GOV.UK's seat-belt page groups 12 or 13, or younger and over 135cm as the cohort that must wear a seat belt rather than sit in a child seat.

Some families keep a high-backed booster after the legal threshold because the adult belt still sits on the neck or stomach. That is a choice about belt path, not a second legal height. UK law does not require a child seat after 12 or 135cm (whichever came first).

How do I check 135cm at home?

1. 1
   Measure standing height Shoes off, heels to the wall, a firm book or ruler to the crown of the head. Mark the wall and measure to the floor in centimetres.
2. 2
   Compare with 135cm, not with age If the mark is 135cm or above and they are still under 12, height has already ended the child-seat duty. If they are 12 and the mark is 128cm, age has already ended it.
3. 3
   Re-check after a growth spurt The legal switch is whichever threshold arrives first. A child who was 132cm at the last school holiday may have crossed 135cm by the next term.
4. 4
   Keep using a seat until that day Until one of the two figures is reached, GOV.UK still expects the correct child car seat in a car or van, subject only to the published exceptions.

Is 150cm the UK legal height?

No. The figure on GOV.UK is 135 centimetres. Some child seats are sold with a 150cm upper height because that is how those models are approved, and some other countries use a higher legal mark. That does not rewrite the UK statute-style rule on GOV.UK.

If a seat's label allows use up to 150cm, you may keep using that seat after 135cm. You are not required to. Once 12 or 135cm has arrived, the legal minimum is an adult belt where one is fitted.

In shortIn short: UK law is 12 or 135cm, first one wins. Tall and under 12: adult belt. Twelve and still short: adult belt. 150cm is not the UK legal height.