What Car Seat Should My Child Be Using?

Choosing the right car seat for your child can feel overwhelming. With different seat types, regulations, and advice online, many parents simply want to know one thing: what seat should my child actually be using right now?

The answer depends on your child’s height, weight, age, and development, but most children will follow a similar progression through different seat types. The aim is always to ensure your child is travelling in a restraint that fits their body properly and offers the best protection in a crash.

Starting From Birth

For newborns and young babies, the first seat is usually either:

• a rear-facing infant carrier, or

• a fixed rear-facing seat suitable from birth

Infant carriers are designed specifically for small babies and typically last until around 75-87cm or 13kg, depending on the model. They provide important support for a baby’s developing head, neck, and spine, while keeping them safely rear-facing.

Fixed from-birth seats are another option and remain installed in the car. Some parents choose these if they plan to skip the carrier stage.

Both options allow babies to travel rear-facing, which is the safest way for infants and young children to travel in a car.

Moving to a Larger Rear-Facing Seat

Once a baby outgrows their infant carrier, the safest next step is usually a larger rear-facing seat.

Rear-facing travel protects a child’s head, neck, and spine by supporting the whole body and spreading crash forces across the back of the seat. This greatly reduces the strain placed on the neck during a collision.

Many modern extended rear-facing seats can accommodate children up to 125cm or 36kg, which for some children allows them to remain rear-facing until around 6 or even 7 years old.

Although UK law allows children to forward-face from 15 months, this is simply the legal minimum. It is safest for children to remain rear-facing for as long as possible within the limits of their seat, ideally up to 125cm or 36kg where possible.

When is a High Back Booster appropriate?

A high back booster (HBB) uses the vehicle seatbelt rather than an internal harness, so the child must be big enough for the seatbelt to fit correctly and mature enough to sit properly for the entire journey.

As a general guide, most children should meet all of the following minimum criteria before moving into a high back booster:

• 5 years old or older

• 18kg or more

• 105cm or taller

• Able to sit sensibly with the seatbelt positioned correctly throughout the journey

These are minimum requirements, not targets. Many children benefit from remaining rear-facing or harnessed beyond this point.

Although the law allows boosters from 100cm and 15kg, this is simply the legal minimum and does not mean a child is developmentally ready to rely on the vehicle seatbelt.

High back boosters should ideally be used until 150cm, as they position the seatbelt correctly and provide important protection for the head, neck, and torso, as well as side impact protection.

In some situations, a backless booster may be used once a child has outgrown their high back booster but still needs help achieving a safe seatbelt fit. These do not provide the same level of protection as a high back booster, but they can help position the seatbelt correctly until the child passes the 5-step seatbelt test.

When Can My Child Stop Using a Car Seat?

In the UK, children must legally use a child seat until they are 135cm tall or 12 years old, whichever comes first.

However, simply reaching this legal requirement does not mean the adult seatbelt will fit safely. Adult seatbelts are designed for bodies around 150cm tall, which is why many children still need a booster beyond the legal minimum.

The safest way to check whether your child is ready to travel without a booster is the 5-step seatbelt test, which looks at how the seatbelt fits across the child’s body, if their feet are flat to the vehicle floor, and whether they can sit correctly for the entire journey.

Most children do not pass this test until around 150cm tall.

In some vehicles, a child may reach 150cm but still not pass the 5-step test due to seat shape or belt geometry. In these situations, a backless booster may sometimes help improve seatbelt positioning until the child passes the test.

Every Child Grows Differently

Children grow at different rates, which means two children of the same age may require completely different seats.

Regularly checking your child’s height and weight and choosing a seat that suits their growth pattern helps ensure it will last long enough to reach a safe high back booster age.

If you are unsure which seat is most appropriate for your child, specialist retailers and evidence-based car seat communities can help guide you through the options.

FAQs

Is age the best way to choose a car seat?

No. Height and weight are more important than age when choosing the correct seat. Two children of the same age can be very different sizes, which means they may need different seats.

Is it safe to forward-face after 15 months?

Fifteen months is the legal minimum, not the safest option. Rear-facing provides significantly better protection for the head, neck, and spine and should be used for as long as possible within the limits of the seat.

When should my child move to a high back booster?

A child should usually be at least 5 years old, 18kg, and 105cm, and able to sit sensibly with the seatbelt correctly positioned for the whole journey. These are minimum requirements, not targets.

Why should high back boosters be used until 150cm?

High back boosters help position the seatbelt correctly across the body and provide protection for the head and torso. Most children do not fit the adult seatbelt properly until around 150cm tall.

What is the 5-step seatbelt test?

The 5-step test checks whether a child can safely use the adult seatbelt without a booster. It looks at whether their back sits against the seat, their knees bend at the seat edge, and whether the lap and shoulder belts sit in the correct position across the body.