A Parents’ Guide to Car Seat Laws in the UK

To prevent serious injury in the case of a collision, vehicles are legally required to be fitted with seatbelts. However, car seatbelts are tested and designed to fit people over 135cm tall securely.

For this reason, seatbelts do not provide a safe level of protection for children. Without a car seat, a seatbelt can cause severe or even fatal injuries to a child in the event of a crash due to its incorrect positioning on their body.

On a child, a standard seatbelt’s shoulder belt sits too close to the neck area, where their spinal cord and vital arteries are vulnerable. Instead of securing the waist, the lap belt runs across a child’s stomach and can result in organ damage in a collision.

Therefore, car seats are vital for ensuring the safety of children while travelling in a vehicle.

Car seat laws in the UK state that any child under the age of 12 or below 135cm in height must use an appropriate child car seat while in a vehicle. There is also a list of car seat requirements that must be met to be suitable for use and to comply with UK car seat law.

Firstly, the car seat must conform to the EU standard for the child’s weight or height and be correctly fitted according to the manufacturer’s instructions. You must also only use a car seat approved by EU legislation, indicated by a label with a circled capital ‘E’.

The car seat must also be compatible with the vehicle it is used in. This means the seat should be secured with a standard diagonal belt seat strap or ISOFIX anchor points.

Car seat law in the UK also states that car seats or booster seats must not be used on side-facing seats and should only be fitted in the front passenger seat if the front airbag is deactivated.

In addition, since March 1st 2017, all new backless booster seats are only suitable for children taller than 125cm or weighing more than 22kg.

Children under 15 months must always use a rear-facing car seat. This is to best protect them from injury in the case of a collision, as this position mitigates a large amount of the shock.

Most child car seats are divided into groups based on your child’s weight. These are stated in the United Nations car seat regulations and apply to children from birth until they are either 12 years old or 135cm tall. The weight groups are:

• Group 0/0+ - Newborn to 13kg (0-15 months old)
• Group 0+/1 – Newborn to 18kg (0-4 years old)
• Group 0+/1/2 – Newborn to 25kg (0-7 years old)
• Group 0+/1/2/3 – Newborn to 36kg (0-12 years old)
• Group 1 – 9kg to 18kg (9 months to 4 years old)
• Group 1/2/3 – 9kg to 36kg (9 months to 12 years old)
• Group 2/3 – 15kg to 36kg (4 years to 12 years old)
• Group 3 – 22kg to 36kg (From 5 to 6 years old and more than 125cm in height)

You should not move your child up to a car seat in the next group before they reach the maximum weight or height stated. An incorrectly fitting seat can result in severe injury for your child in a collision.

You can check if your weight-based car seat is suitable under UK car seat law by checking the label for a circled capital ‘E’ and ‘ECE R44’ printed on it.

Height-based car seats, also known as i-Size seats, are separated into four types based on your child’s height. These groups are:

• i-Size baby – Newborn to 85cm (From 0 to 15-18 months old)
• i-Size baby and toddler – Newborn to 105cm (0 to 4 years old)
• i-Size toddler and child – 61cm to 105cm (15 months to 4 years old)
• i-Size child – 100cm to 135cm (4 to 12 years old)

i-Size is the new European standard for child car seats and require your vehicle to be equipped with Isofix connectors. All i-Size seats must be used in a rear-facing position until your child is 15 months old. You can check if an i-Size seat is suitable under UK car seat law by checking its label for a circled capital ‘E’ and ‘R129’ printed on it.

While you'll often see car seat rules mention age, this is more of a general guideline to help parents guage what their child might need. It's not a legal standard on it's own and safety regulations are strictly based on weight or height. 

The law states that a child must use a car seat until they're 12-years-old or are 135cm tall, whichever happens first. 

So, while the age limit for car seats in the UK can help you narrow down car seat options, age isn't the only factor that impacts whether a child needs a car or booster seat or which type they might need. 

There are some key differences between car seats and booster seats that are important to know to ensure you’re using the correct one for your child.

Car seats, designed for babies and younger children, secure your child with a 3- or 5-point seatbelt harness. These harnesses are designed to distribute pressure in the case of a collision, so a child’s vital areas are better protected. Car seats are equipped with a hard, curved backrest with raised edges, designed to offer the most protection possible.

Booster seats, designed for children over 15kg and up to 12 years old, provide a raised seat that ensures the seat belt is correctly positioned on a child’s body. This allows the seatbelt to protect the child from impact as intended.

In the UK, booster seats requirements are also based on height and weight, with age as a guideline to help parents pick the right option.

Just like a car seat, children must use a booster seat until they're 12 years old or 135cm tall (whichever happens first). There are two main kinds of booster seat - backless and high-back - and there are slightly different weight and height requirements for each booster seat.

Since March 2017, backless booster seats can only be used by children who are taller than 125cm and weigh more than 22kg. Older backless booster seats (made before the 2017 regulations came in) can still legally be used by children weighing between 15 and 36kg, but experts recommend following the new guidance for safety.

High-back booster seats can be used by children between 15 and 36kg.

In the UK, if you are caught driving with a child in the vehicle without a car seat, or with one that is unsuitable or incorrectly fitted, police can issue an on-the-spot fine of up to £500 if the case is referred to court.

It’s important to note that it’s the driver’s responsibility to ensure that all passengers, child or adult, are correctly and safely strapped in their seats, so be sure to check before setting off.

Other legal requirements for car seats include making sure it meets EU safety standards. All car seats must be approved by the EU to be legal in the UK. They'll have a label with a capital 'E' in a circle and the text 'ECE R44' on them. 

Aside from fines and penalties, making sure you're following car seat regulations will also help keep children safe when you drive if anything happens. 

According to the UK government website: “Children must normally use a child car seat until they're 12 years old or 135 centimetres tall, whichever comes first”. While this is often always the case, there are some scenarios in which a child does not legally have to use a car seat:

Taxis
If the driver doesn’t already provide one, it is permitted for a child to travel in a taxi or mini-cab without a car seat. They must still wear a seat belt, however.

Coaches or minibuses
The same rules apply to coaches or minibuses. In these vehicles, children must travel in the rear seats if a child car seat or an adult seat belt isn’t fitted.

Unexpected journeys
If you and your child(ren) are in a situation where you need to make an unexpected and necessary journey over a short distance, a child over the age of three is permitted to use an adult seatbelt.

You cannot take a child under the age of three on an unexpected journey in a vehicle unless it’s in a licensed taxi or minicab and the child travels in the rear seat without a seatbelt.

When there is no room for a third child car seat
In a situation where there is no room for a third child car seat in the rear of the vehicle, children under three can travel in the front seat in the correct car seat. If the child is over three years of age, they are permitted to sit in the back using an adult seatbelt.

Emergency vehicles
When inside a police or other emergency service vehicle, children may ride without using a car seat or booster seat if suitable restraints are unavailable.

Where is the best place to put a car seat?
The best place to put a car seat in your vehicle to offer the most protection for your child is the rear middle seat due to its distance away from passenger-side airbags and front seats.

When should you change from a rear to a forward-facing car seat?
You should not change from a rear-facing seat to a forward-facing car seat until your child is at least 15 months old. Research has shown that babies and young children should remain in a rear-facing seat for as long as possible, as the shock from an impact is greatly reduced in this position.

Are backless booster seats legal in the UK?
Backless booster seats are permitted under booster seat laws in the UK as long as the child weighs more than 22kg and is taller than 125cm.

Can children sit in the front in a car seat?
Under car seat laws in the UK, it is legal for a child to sit in the front seat if they are using the appropriate restraint. However, if you are using a rear-facing car seat, you must NEVER secure a child in the front seat if the vehicle has a passenger-side airbag. In the case of a collision, this can cause serious injury and/or death upon activation.

What are the specific height requirements for booster seats in the UK?

In the UK, a child must use a booster seat until they're 135cm tall. While there's no minimum height requirement for high-back booster seats, children must be over 125cm to use a backless booster seat since new regulations came into effect in March 2017. 

What are the legal age limits for different types of car seats?

While UK car seat laws are based mainly on height and weight, there are some minimum age guidelines to help parents/guardians choose the right type of car seat. 

• Rear-facing: From 0 months to 15 months old
• Forward-facing: From 15 months old to 4 years old
• Booster seats: From 4 years old to 12 years old
• Seatbelts/ No car seat: Children aged 12 and over (or those who are over 135cm tall) don't need to use a car seat

How do the legal requirements for car seats differ between i-Size and weight-based systems?

Both systems are legal in the UK and differ in the criteria they use to determine which car seat is right for a child. i-Size measures children by height and recommends keeping them in rear-facing car seats until they're at least 15 months old. Weight-based measures by weight and recommends switching from rear to forward-facing car seats from 9 months old. 

i-Size is the newer system and is considered safer. Once you start following one system, you have to stick to it - they cannot be mixed. 

So there you have it, everything you need to know about car seat laws in the UK. If you’re planning on taking the family on your next road trip, but haven’t brought the right safety equipment, worry not! At Avis, we stock a wide range of quality baby, infant and child seats which you can select at the time of booking.

If you’re new to driving in the UK or would benefit from some additional advice while on the road, take a look at our UK road rules page. With everything from speed limits to traffic signs, our simple, straightforward guide provides everything you need to know to make driving in the UK as safe and stress-free as possible.

And if you’re looking for inspiration for your next unforgettable road trip, check out our great drives guide. Our experts have compiled some of the very best excursions around the world to enjoy, from day trips to multi-stop adventures.

So, whether you're planning a family trip to Cornwall or picking up a car from the airport at Heathrow or Manchester, reserve your car with appropriate car seats in advance with Avis.