How long should a child be rear-facing in a car seat?

Fact checked by car seat safety experts Julie Dagnall and Claire Waterhouse at Child Seat Safety

Regardless of your child’s age, securing them properly in a car seat is one of the most important things you can do to keep them safe in the car.

The Royal Society for the Prevention of Accidents (RoSPA) emphasises that a vehicle’s seat belts don’t fit babies or older children at all, making them ineffective and potentially harmful in the event of a collision if you use them without a car seat.

RoSPA goes on to explain that children's bodies are different from adults’. They have unique proportions, bones that are still growing and a skeletal structure that doesn't shield their internal organs as well. That's why your child's neck and head need extra support. 

As your child gets older, their restraint systems, including car seats, high back booster seats and booster cushions/backless boosters need to adjust to these changes until regular seatbelts (that fit their bodies properly) can keep them safe.

A car seat is essential for ensuring your child’s safety during car journeys. Consequently, in the UK (England, Scotland, Wales and Northern Ireland), the law requires that children must use a properly fitted car seat appropriate for their height or weight when travelling in a car or van. There's also the two-hour car seat guideline to take into consideration when driving long distances with your baby on board.

But with all the different car seats available, you might be wondering where to start and which one to purchase first. Understanding why rear-facing car seats are important and how long your child should stay rear-facing can help you make an informed decision.

Read next: Best 360 spin car seats

How we researched extended rear-facing car seats 

To learn more about infant car seat regulations in the UK as well as the safety benefits of extended rear-facing, we consulted experts Julie Dagnall and Claire Waterhouse at Child Seat Safety. They are the national advisors for child car seats for Road Safety Great Britain and run the UK's first and only IOSH and CPD accredited child car seat training courses. 

We also tapped into the knowledge of industry experts Axkid and Rear Facing Toddlers, and learned about the latest car seat safety research at the Axkid Child and Safety Conference 2024.  

Additionally, we looked at the results of the Swedish Plus Test, a rigorous safety standard that evaluates the crash performance of rear-facing toddler car seats either up to 18kg or 25kg when approved to ECE R44.04, or up to 105 or 125cm when approved to UN R129.

Read on to find out how long your child should be rear-facing and why rear-facing is so important for your child’s safety whilst travelling in a vehicle.

How long should a baby be rear-facing?

As your child grows, you'll need to change the direction their car seat faces and how they sit in it. But to start with, the UK law requires that you must use an appropriate car seat for your child until they are 12 years old or 135cm tall, whichever comes first. Thereafter, a seat belt is compulsory.

When it comes to height- and weight-based car seats, Rear Facing Toddlers says that in an R129 car seat (which has height limits), children must rear-face until they are at least 15 months old or 76cm tall, regardless of their weight. Older car seats, which fall under the R44.04 regulation introduced in 2006, allow children to be forward-facing from 9kg regardless of their age.

From a safety point of view, R129 car seats are required to pass rigorous side-impact tests which aren’t compulsory in R44.04 testing. They also offer additional safety features such as compatibility with ISOFIX installation for easier and more secure fitting, and advanced testing protocols to ensure higher safety standards. For an in-depth explanation on the difference between height and weight-based car seats that fall under both the R129 and R44.04 regulations, be sure to read our updated guide on car seat regulations in the UK.

Read next: Best car sunshades for babies

What do the experts say?

While it’s legal to switch to a forward-facing car seat after 15 months, experts at Child Seat Safety suggest keeping your child rear-facing for longer, ideally until they are at least four years old. “Children are safer to rear-face in a vehicle for as long as possible, and they vary in their height and weight, so what might be okay for one child might not work for another,” explains Director at Child Seat Safety, Julie Dagnall.

“Only when a child's development is appropriate for them to face forward, and they have outgrown the rear-facing height and weight requirements of their seat (preferably not before the age of four), should they be placed in a forward-facing position. If your little one is under the age of four, you could consider a car seat that can be used both rear-facing and forward-facing. This way, you can keep them rear-facing for longer and switch to forward-facing later,” she adds.

Another option is to choose an extended rear-facing car seat like the Be Safe Stretch that allows you to rearward-face up to the age of seven years old (or 125cm).

Read next: Should you hire a car seat and is it safe?

What are the benefits of extended rear-facing?

Curious about the advantages of extended rear-facing? According to Lotta Jakobsson, Senior Technical Specialist in Injury Prevention at Volvo Car Group, research shows that while rear-facing car seats are widely accepted globally, many children outside of Sweden often transition to forward-facing car seats too early in relation to their development.

This shift is frequently driven by ‘comfort’ factors, such as the perceived convenience of forward-facing car seats, space constraints for rear-facing models and increased legroom for children facing forward. However, the safety benefits of keeping a child rear-facing for longer far outweigh these supposed drawbacks – which are being worked on continuously by some car seat manufacturers to improve children’s comfort whilst rear-facing.

Axkid research highlights a crucial point: children's heads are proportionally heavier than adults', making their necks more vulnerable in the event of a collision. Forward-facing car seats subject children to up to five times greater forces on the neck during frontal crashes compared to rear-facing car seats.

“In a forward-facing car seat, a child's head is restrained and stabilised mainly by their neck in the event of a collision, causing high stress on the head and neck that can lead to serious head injuries. In contrast, rear-facing car seats restrain the head and body together, distributing the load more evenly and reducing stress on the neck, thus providing better protection for the head,” says Jakobsson.

Supporting this, a Swedish study found that rear-facing car seats lower the chance of injury by 90% compared to being unrestrained. Forward-facing car seats, when used with proper seat belt positioning, reduce the risk of injury by 77% for children aged between four and 10 years old.

Read next: Best travel systems for newborns

Here are the benefits of extended rear-facing car seats

• Head stability: Rear-facing car seats protect a child from head injuries by preventing the head from hitting surfaces such as the car door or window. They also ensure that a child's head always remains within the protective shell.

• Even distribution of crash forces: Rear-facing car seats cocoon a child in a protective shell, shielding them from debris like broken glass or car parts. They distribute crash forces evenly over the back, which is the strongest part of a child’s body, which minimises the impact on any single area.

• Better spinal support: By cradling a child's entire body, rear-facing car seats provide enhanced support for the spine and reduce the likelihood of spinal injuries. During side-impact crashes, rear-facing seats offer superior protection by keeping the child’s body better contained and shielded.

What exactly is an extended rear-facing car seat?

“Extended rear-facing car seats allow a child to travel rearward (facing the back of the car) until they are an appropriate height/weight to turn them forward-facing,” explains Director at Child Seat Safety, Claire Waterhouse. They tend to be larger seats and may require additional lower tethers (or anchor points) to secure the seat in place.

“Many extended rear-facing car seats can be fitted using the vehicle’s seat belt and this means they can hold a heavy child compared to an ISOFIX version. This would give you longer to keep your child rear facing and can be better value for money,” she adds.

Choosing the right rear-facing car seat depends on what best suits your family's needs. Unlike baby car seats, which are often carried in and out of the car and travel-system compatible, you might need a rear-facing car seat that's easy to move between cars and simple to install and stay put if you have two vehicles. There are many options available, so it's important to find the one that works best for you.

Here are a few more options to consider:

Read next: Best toddler car seats

Transitioning to forward-facing: when is the right time?

The expert verdict is clear: children are safer rear-facing in an extended rear-facing car seat that meets R129 or R44.04 regulations for as long as possible, ideally until the age of four but preferably until age six or seven. Thereafter, they can move to a forward-facing position in an appropriate car seat that meets the same safety standards.

Child Seat Safety recommends that your child continues to use a high- backed booster seat until they 150cm, even though the law states they can stop using one at 135cm, this is because the vehicle seatbelt is designed for passengers who are 150cm or taller and will then fit them correctly.

Real-world data presented at the 2024 Axkid Conference shows that children using high-back booster seats are much safer in cars. These seats cut the risk of injury by 77% compared to kids who aren't restrained at all. For children aged between four and eight years old, using a high-back booster makes them 45% less likely to get injured in a car compared to just using a seatbelt.

In front-end crashes, high-back boosters almost eliminate the risk of abdominal injuries. They also offer better protection in side-impact collisions, no matter if the impact is on the near side or far side. Overall, high-back booster seats are a crucial tool for keeping children safe on the road.

“Once a child reaches 150cm, a booster cushion (or backless booster) can be used if the vehicle has safety features such as curtain airbags (a type of airbag that deploys from the roof area above the windows of a vehicle during a side-impact collision or rollover event) and side airbags in the passenger seat, as a child would be tall enough to benefit from these protections in the event of a collision,” says Julie Dagnall of Child Seat Safety.

What do high-back booster seats do?

The role of a high-back booster seat is to ‘boost’ - in other words, to raise your child into a good lap and shoulder belt position. It’s also designed to:

• Provide comfortable cushion length

• Offer lap belt guides to help position the lap belt towards the pelvis

• Offer side support and protection for comfort and an upright sitting posture

“The booster’s main purpose is to raise a child in a good position for good lap belt geometry, to help reduce the risk of submarining in frontal impacts and for a more comfortable and safe shoulder-belt position,” says Lotta Jakobsson.  

Submarining is when a child slides under the seat belt during a crash, which can cause serious injuries. A high-back booster seat or cushion helps prevent this by raising your child to the right height, so the seat belt fits properly. This keeps the lap belt across their hips and the shoulder belt across their chest, making them safer and more comfortable.

About the author

Tammy Jacks is a distinguished researcher and writer in the field of child safety, with a notable focus on the critical domain of baby travel including car seats and strollers. Her extensive expertise and commitment to child safety have made her a trusted authority in providing comprehensive insights and guidance to parents and caregivers looking for the right stroller, travel system or car seat for their children.

As a seasoned school runner and mum to a nine-year-old, Tammy has personally tried and tested numerous buggies, strollers and car seats over the years, across all age categories.