Why do I need a baby car seat?
Using a baby car seat when you travel in a vehicle with your child is the law. Your child must be in a car seat until they are 12 years old (or 135cm tall), whichever comes first.
What size car seat is suitable for newborns?
UK legislation states that a child needs to be in a car seat until they are 12 years old or 135cm tall (whichever comes first). Car seats are based on either weight or height, depending on which regulation they follow.
Seats under the R44 regulation are weight-based and seats under R129 are height-based. Both types of car seats are available to buy and legal to use in your vehicles in 2026, but R44 seats will likely be phased out over the coming years.
R44 car seats come in stages:
Group 0+: birth to 13kg (around 12 to 15 months)
Group 0+/1: birth to 18kg (around 4 years old)
Group 0+/1/2/3 (multi-stage): birth to 36kg (around 12 years old)
R44 car seats can be fitted in one of two ways: via your car’s ISOFIX points (which secures the seat directly onto the vehicle chassis) or alternatively with your car’s adult seatbelt which is handy if you have an older vehicle which doesn’t have ISOFIX anchor points as standard.
Group 0+ car seats are usually travel system-compatible and often come with a newborn insert for small babies. Group 0+/1 seats are designed to adapt to your growing child and are generally bigger and heavier than Group 0+ seats, which means they are typically designed to stay in one car. Group 0+/1/2/3 seats are combination car seats that grow with your child all the way up to 12 years old.
It’s worth noting that whilst R44 seats are perfectly legal, they generally don’t have the same side impact testing as seats that conform with the more recent R129/i-Size standard.
Claire Waterhouse of Child Seat Safety says, “While under ECE R44/04 there is no requirement to do a side-impact test, some manufacturers do make seats that have this safety feature. You should look for it regardless, as well as the seat’s overall crash test rating.”
What is i-Size?
The R129 standard (also referred to as i-Size) was introduced in 2013 and includes more detailed safety tests for head/neck protection and side-impact crashes. In an R129 i-Size car seat, suitability is based on your child’s height rather than their weight, making it easier to see when your child is outgrowing their seat.
R129 seats use ISOFIX to safely secure your seat to the main chassis of your car. This reduces the risk of installing the seat incorrectly but does require the addition of an ISOFIX base which can increase the cost.
Read next: Tips for keeping you and your family safe on the road
What's the difference between R44 and R129 car seats?
R44 regulation car seats
Classification based on weight
Rear and front impact testing
Can be fitted using seat belt or ISOFIX points
Seat must be rear-facing until your child weighs 9kg
R129 regulation car seats (i-Size)
Classification is based on height
Rear, front and side-impact testing
Seat is attached with ISOFIX points
Seat must be rear facing until your child is older than 15 months
Read next: The latest car seat regulations, including R129 and R44.04
What should I look for when buying a baby car seat?
Choosing the right car seat for your baby can be slightly overwhelming, but here are the main things you need to consider when making your choice:
R44 or R129 compliant?: Be sure to look at which standard the car seat has been measured to. Whilst R44 car seats are still perfectly legal, you may prefer the enhanced side impact testing on newer R129 (i-Size) car seats.
Ease of installation: How easy is the car seat to install in your vehicle? Does it offer a choice of seatbelt or ISOFIX fitting and, if ISOFIX only, is this compatible with your car? It’s also worth considering how heavy and bulky the car seat is, particularly if you are going to be installing the car seat on your own.
Weight: If you are likely to be carrying your car seat to and from the car or swapping between vehicles regularly, you should consider how heavy the seat is to carry. Car seats such as the Maxi-Cosi Coral (see above) are ideal for parents with back complaints as the lighter inner liner can be removed without you need to take the entire seat out of the car.
Safety features: What safety features does the car seat offer? How does it perform in Which? and ADAC crash testing? Whilst older seats tend to focus on front-on collisions, seats tested to the R129 standard offer enhanced side impact protection, although in some cases these need to be manually triggered.
Plane compatibility: Not all car seats can be taken on a flight, so if you’re planning to travel regularly with a baby under 12 months, you’ll need to look out for seats that are TÜV-approved for aeroplane use.
Is it travel system compatible?: Do you do a lot of walking and hope to attach the car seat to your pushchair? Not all car seats are travel system-compatible, and those that are typically to have a shorter lifespan of around 12 to 15 months. If you tend to travel more in the car, you may get better value for money from a fixed extended rear-facing car seat, lasting until your child is around four years of age.
Is the base included?: Whilst some car seats include an integrated base, others need bases that are sold separately. Some car seats can be fitted with the seatbelt alone, but they are only truly i-Size-compliant if installed on the base via ISOFIX adapters. You should also consider whether the base is compatible with the next-stage car seat you intend to use as this improves the overall value for money and longevity of use.
How long does it last?: How long do you want to use the seat for? Whilst lie-fat seats such as the Maxi-Cosi Jade only last around six months, others such as the Cozy N Safe Arthur (see both above) can see you through till your child is 12 years old.
Does the seat swivel?: If opting for a fixed car seat that stays in the car, you may want to look out for a swivel seat, which allows the seat to be turned to the door side so that you can easily place your child in the seat. This prevents stretching over the seat and is helpful for parents with back problems or those recovering from a c-section. They also offer a relatively seamless transition between rear- and forward-facing when the time is right.
What is ISOFIX?
ISOFIX is a structural system built into the car that has fitting points to attach an ISOFIX car seat. The seat is latched onto the ISOFIX points and then braced by using either a support leg or a top tether.
You can only use an ISOFIX seat in a car with ISOFIX fittings and not all vehicles have them, especially older models. It is important to check the child car seat manufacturer’s compatibility list as there are some vehicle features that can make the child car seat incompatible.
You’ll be able to find out if your car has ISOFIX attachments by looking for tags or labels on the base of the seat or by contacting your manufacturer.
Is ISOFIX safer than a seatbelt?
Where possible, installing a seat with ISOFIX is far safer than installing with a seatbelt alone. Seatbelt installation comes with a far higher risk of installing correctly, for example, twisting the belt or not pulling it tight enough to secure the seat.
ISOFIX connections also offer more stability and reduce the amount of movement in the seat, providing better protection for your child in an accident, particularly a side-on impact.
Read next: The best baby carriers to buy, as rated by Mumsnetters
What is an extended rear-facing car seat?
An extended rear-facing car seat is a car seat that can remain reward-facing for longer than the minimum 15-month duration.
By law, babies need to remain rear-facing until they are 15 months old, after which they can be turned forward-facing. Whilst many parents turn their babies forward-facing as they grow (usually so they can see out the window), according to car seat safety expert and Chief Executive of Good Egg Car Safety, Jan James, it is far safer to keep your baby rearward-facing as long as possible. Some experts believe it to be as much as five times safer.
Some car seats such as the Joie i-Spin 360 i-Size and Britax Römer Dualfix Plus i-Size are classed as extended rear-facing car seats. They are suitable from birth to four years and offer rearward-facing travel for the entire duration of use.
What is a 360-degree or swivel car seat?
A 360-degree or swivel car seat can be turned to the door side for easy placement of your child in the seat, which can be helpful for parents who have challenges with back pain or for whom reaching across the backseats could be difficult.
A swivelling seat also helps make a seamless transition from rearward- to forward facing when the time is right.
Some swivel seats can rotate a full 360 degrees, while others simply rotate 180 degrees to move between front and rear-facing installation without needing to remove or reinstall the base.
How long can a baby stay in a car seat?
A study by the Lullaby Trust in October 2016 found that babies should only be kept in a car seat during travel for a maximum of two hours and be removed at the earliest opportunity. For babies under three months, experts recommend they are only kept in a car seat for 30 minutes at a time.
What is the two-hour rule?
The two-hour rule recommended by manufacturers suggests that babies should not be kept in a car seat for longer than two hours at a time. This is because the raised and scrunched-up position in a car seat can put a strain on the baby’s still-developing spine and restrict airflow to the baby’s lungs.
It is recommended that, on longer journeys, you take regular breaks and remove your child from the seat, allowing them to stretch their legs and realign their spine. As tempting as it may be, you should not allow your child to sleep in the car seat when you reach your destination and should be removed to sleep on a firm, flat surface.
How much does a baby car seat cost?
Prices range from £30 to over £400, but it's not always the case that the most expensive car seat is the best.
All car seats have to pass the minimum safety criteria laid out by the R44 regulation to be legally sold, but many of the bigger brands do their own independent tests at higher speeds. Some have even passed the Swedish Plus Test, which is the world's strictest car seat test.
Overall, consider your budget and always check independent reviews before making any decision.
Read next: The best double buggies, as rated by parents
Can you use a second-hand car seat?
A car seat's main job is to protect your baby and, for that purpose, it tends to be a single-use item. You can use a car seat until you have an accident, at which point it must be thrown away and replaced.
While second-hand seats aren't necessarily unsafe, if you buy a seat from someone you don't know you have no real way of knowing the seat's history. This may not be the case if it's been passed down from a relative or a friend, but even if the seat looks fine, it could still have suffered invisible damage that has made it weak or unsafe.
Margaret Bolt, a qualified Child Seat Safety Adviser and founder of Rear-Facing Toddlers says, "It isn’t a case that the seat will suddenly become less robust or less likely to withstand an accident, but, as a seat gets older, it becomes more difficult to know its history. It may have been passed from owner to owner, its crash history might not be known, instructions may be missing or spare parts unavailable.”
As such, car seat safety experts generally recommend never buying a secondhand car seat.
Can you take a car seat on a plane?
If a child is under 18kg, then using a car seat on board a plane is the safest way to travel but the seat must be certified for use by either the CAA (Civil Aviation Authority) or the FAA (Federal Aviation Administration) or be TÜV-approved. Check with your airline for their guidelines first. Airlines will also have car seat width restrictions in place and these can vary by carrier. Bear in mind that you'll need to book a separate seat for your child to travel in this way, as opposed to on your lap.
When it comes to travelling abroad, make sure you understand the law in the country you are travelling to. EU seats can be used throughout Europe, and also in the Middle East, some parts of Africa, Asia and New Zealand. They're technically illegal to use in the USA, Canada and Australia, although they may be permitted for a holiday.
A car seat can often also be taken in the hold free of charge, but make sure it's well padded and covered to avoid being damaged.
If you're not travelling with a car seat but want to use one on arrival, you may want to consider ordering a new seat from a local retailer at your destination and see if it can be delivered to where you're staying or to the car rental place.
We don’t recommend hiring seats as they're often old, may not be suitable for your child and you won't know the history of them.
Read next: The best family holiday destinations, according to Mumsnet users
6 minute car seat safety video
Here, car seat safety expert Jan James from Good Egg Car Safety answers some of the most frequently asked car seat questions:
What is ISOFIX, and is it safer than a seat belt? (00:00:17)
How long can a newborn stay in a car seat? (00:00:50)
When can babies legally go in forward-facing car seats? (00:01:43)
How tight should the straps be? (00:02:37)
Why buy a £300 car seat when you can get one for £30? (00:03:08)
Can an infant car seat be in the front seat of a vehicle? (00:04:34)
Can I use a secondhand car seat? (00:05:01)