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Baby & child.

Updated: 2 Sep 2021

How to buy the best baby or child car seat

Stop car seat confusion with our guide to how much you should spend, whether to go for a group seat or i-size and find out why car seats jargon, such as Isofix, should matter to you
Hannah Fox

Car seats are confusing to buy. There's so much jargon to understand, everything from Isofix to i-Size, and booster seats to car seats bases.

In this guide we'll explain everything you need to know to get you started on buying the safest baby or child car seat.

Video: how to buy the best car seat

Watch our comprehensive video to learn about car seat groups and i-size car seats, when you need to move up to the next child car seat, tips for shopping, fitting more than one car seat in a car and much more.

Which newborn or baby car seat?

All children need to use a car seat from birth until 12 years old (or until they are 135cm tall, whichever they reach first).

Child car seats are designed to protect children's soft bones and vulnerable internal organs at each stage of development. 

Babies need different levels of protection to toddlers and older children, so when you’re buying your first newborn or baby car seat you need to make sure you're getting one that is suitable specifically for newborns and younger babies.

The car seat you buy needs to meet EU standards. Your child needs to be in the correct category of seat for his or her age and size. All babies start off in a rearward-facing infant car seat. 

Here we explain the differences between baby vs child car seats in more detail and to find out more about why travelling backwards is a vital part of preventing injuries in a crash. 

You'll need to decide whether you want an infant carrier that can be used a part of a travel system on a pushchair, and you'll also need to consider whether you want a car seat that can be secured to the car by Isofix connectors, the car seatbelt or a base. And see our top 10 baby car seats

Group 0+, i-Size or multigroup seat?

Click below and slide through the gallery to help you decide what type of car seat is best for your new arrival. 

For more in-depth information read our guide to how to buy a car seat that fits your car. Here we detail the many factors that affect how well a car seat fits into your car and what to check before buying a car seat that will suit your lifestyle.

What are car seat groups?

Child car seats are bought in two ways: either according to your child's car seat weight group or according to the height of your child. So Group 0+ is from 0-13kg – that's from birth to about 12-15 months old. It's possible to buy seats that combine one or more groups, for example group 0+/1, 0-18kg, 40-105cm, or from birth to around four-and-a-half years old. These are known as multi-group or combination seats. 

Find the correct one for you from the different car seat groups.

What is i-Size?

i-Size is part of R129, a new regulation for child car seats that was introduced in 2013. The idea behind i-Size is that all car seats with the i-Size logo will fit in all i-Size approved cars. Your car and your car seat must have Isofix, a fitting system that attaches car seats directly to the frame of your car using connectors. i-Size/R129 seats are based on a child's height (instead of weight). The new seats don't replace the weight-based seats at the moment, they just give you an alternative.

Read more about why an i-Size car seat might be best for you. 

Mum shopping for car seat

Swivel car seats

If you're looking for a swivel baby car seat – that's a car seat with a rotating base – you'll be pleased to know there are now more models than ever that have this feature. Some child car seats have a swivel base to help you put your child into the seat, as you can turn it towards the car's door. Other car seats have a swivel base to make it easier to switch between rearward-facing and forward-facing.

Some car seats have a mechanism to stop the car seat being turned forward-facing too early, but others don't. If there is no way to stop the car seat being turned to face forwards too early, it lost marks in our tests because of the potential for misuse. 

Swivel car seats – see which ones we've crash-tested and advice on buying the right one.

Toddler in car seat

Isofix car seats

Isofix is designed to make installing your car seat quick and easy. All new vehicles feature the system. You simply click the Isofix connectors on the base of your seat into the Isofix anchor points in the car.

These anchor points are metal bar connectors built into the chassis of your car. They are often hidden behind the car's seat padding.

Once the Isofix connectors are clicked together, the car seat is secured by a third point – either a support leg that comes built-in into the seat or seat base, or a top tether (a strap that attaches to a mount somewhere behind the rear seat). Both of these work to stop the car seat tipping forward in an accident.

Find out more about Isofix, top tether, support legs and Isofit.

child sleeping in car seat

Toddler car seats

Babies can move up to a forward-facing Group 1 seat when they reach 9kg, but we think this is far too early because their bodies may not be strong enough. It's safer to leave a baby rear-facing until they are at least 13kg or 15 months old.

Many parents turn their child forward-facing too soon, risking more severe neck and brain injuries in a crash. Extended rear-facing car seats, that let you keep your child rear-facing until the age of four/18kg/105cm, are becoming more common.

Find out more about rear-facing baby car seats and extended rear-facing toddler car seats.

Dad strapping in a car seat

How much should I spend?

You can spend as little as £20 on a child car seat, or anywhere up to hundreds of pounds. 

Our advice would be not to scrimp on a car seat: get the best you possibly can.

We crash test each car seat we review, and it's very rare that we see a cheap car seat that provides enough protection to become a Best Buy.

Many parents don't want to pay hundreds for a first-stage car seat, but a £300 extended rear-facing Best Buy car seat, that will last until your baby is four years old, works out around 20p a day over the lifetime of the seat.

Group 2/3 seats can be cheaper and, as your child gets older, they can withstand the force of a crash a bit better, so this is where you can save money but still get a decent high-backed booster seat.

Our pick of the best car seats

An expensive car seat doesn't always guarantee it's the safest option, though, so check out our best baby and child car seats or log in to see our top picks below. 

  • 82%

    According to the manufacturer, this i-Size infant carrier promises ‘the best in safety, comfort and ease of use’. It’s suitable for babies measuring 40-85cm, which is birth to around 15 months. Read the full review to find out how it scored in our tough crash tests.

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  • 80%

    This child car seat is an extended rearward-facing swivel seat that has been tested not just to the i-Size R129 regulations, but also the Swedish Plus Safety test. Read our full review to find out what this is and whether this child car seat has also impressed in our own tougher-than-the-regulations Which? crash testing.

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  • 74%

    Billed as being ideal for adapting to your growing child, this i-Size high-backed booster car seat should safely take your child from four to 12 years old. Read our review to find out how much protection this car seat offers in a crash, and whether it’s worth investing in.

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(Tables above last updated September 2021)

Dangers of secondhand car seats

Second-hand car seats will have wear and tear that could affect the safety protection for your child. The harness, for example, could have been cleaned with harsh chemicals that can make the fabric deteriorate, or the seat could have been involved in a crash and weakened. These are things you cannot tell just by looking at the seat. It's not worth the risk.  

Older seats may not comply with the latest safety regulations, or have gone through updated safety tests, or might be missing the instruction booklet that tells you how to install and adjust the seat safely.

These tips will get you started, but for more advice on what to do before you buy, read and download our car seat shopping checklist.