Once your child has outgrown their toddler car seat, they will be ready for a booster car seat, which typically lasts from ages 3 or 4 until age 12. You'll often seen these referred to as group 2/3 seats, although most car seats now adhere to the newer safety standards of R129, explained below.


This category of car seats divides into two main types: high-backed booster seats or booster cushions (which do not have a back). The ones we’ve chosen here are all high-backed booster seats as they offer the most support and protection.

Best car seats for age 4+ at a glance

  • Best for abdominal support: Britax Romer Kidfix i-Size Car Seat, £239
  • Best for small spaces: BeSafe iZi Flex Fix iSize, £219
  • Best for growing with your child: Nuna Aace LX, £220
  • Best budget buy: Joie i-Trillo, £75
  • Best for innovation: Maxi-Cosi Rodifix Pro² i-Size, £169.99
  • Best for naps on the go: Cybex Solution T i-Fix, £174.95
  • Best lightweight car seat: Graco Junior Maxi i-Size, £50
  • Best for changing temperatures: Silver Cross Discover i-Size, £175
  • Best for comfort: Cybex Solution G i-Fix, £154.95
  • Best for simple installation: Joie i-Traver, £135

To help you decide what car seat is best for your child (and your car) we’ve extensively researched the market to bring you options from a range of brands at a variety of prices. We’ve quizzed more than 1000 parents about the car seats they’ve used as their kids grow, and rigorously tested and reviewed hundreds of car seats, including more than 50 for age 4+.

We’ve also taken into account safety testing carried out by ADAC, a leading tester of car seats in Europe, which is recognised throughout the industry for its stringent safety standards. ADAC does not test all car seats, and if a seat has not been tested by ADAC this does not make it unsafe to use. However, where a seat in our list has been tested by ADAC we’ve provided the score. In these tests a low score is best, and all the seats on this list that have undergone the testing have scored “Good” or better.

For more recommended car seat options, have a look at our best swivel and rotating car seats too.

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When do I move to a high-backed booster seat?

Car seat standards are generally based on height and weight suitability rather than age, so exactly when you need to move your child into a high-backed booster seat depends on which growth percentile they are on. The seats in this list are often referred to as being suitable from around age 4 but it can depend on the model.

It can be tempting to move to a booster seat as quickly as possible as they tend to be lighter and less bulky than toddler seats, but there is no rush to move your child out of their toddler seat if they still fit. If your toddler car seat has extended rear-facing capabilities, it makes sense to take advantage of that as long as you possibly can. Toddler seats also have a 5-point harness that offers more support for small bodies than the seatbelt used to fasten a booster seat. Some newer seats suitable for toddlers – such as the Axkid One 2 and the Axkid Minikid 3 – can be used until they reach 25kg in weight, which can be age 6 or 7, and there's absolutely no need to change before then.

What is the R129 child car seat safety standard?

While the term 'group 2/3 seats' is still in use and something you may already be familiar with, this refers to the older R44 legislation. Most child car seats (especially newer ones) now comply with the new R129 safety standard. The new R129 standard is the latest in EU/UK safety standards and follows more detailed tests for improved head and neck protection. R129 seats also go through side impact testing and Q dummy crash tests with 32 sensors. Focusing on a child’s height, rather than just weight, it gives a more accurate guide on the safest time to upgrade a child’s car seat.

What to look for when buying your car seat

Fitting– Car seats either fasten using the car seat belt or Isofix connectors that click into your car's frame. Some may also have a tether strap. No one method is safer than another so long as the seat is fitted correctly, but many people find Isofix to be more convenient and straightforward, therefore less prone to error. You will need to check the cars you will be using have Isofix connectors in the right place if you want to use an Isofix seat.

Safety – Safety is obviously the key issue for any car seat. The big change for this age group is that most car seats will no longer have a built-in harness. Instead the child will be secured using the adult seat belt, which will also thread through the car seat in some way. All car seats in the UK will have been tested to one of two European standards, either ECE R44/04 or the newer ECE R129. R129 seats have been tested for side impact as well as front and rear impact collisions.

Longevity – The law requires that children up to 12 years old/135cm in height must use a child car restraint where seat belts are fitted. This means you'll be using this seat for a long time, so you'll want to consider how it adapts and grows with your child.

Weight – Car seats vary significantly in weight: we found some that are under 5kg and others that weigh in at 8kg or so. Think about how often you’re going to remove it from the car, or move it to another. If you’re likely to keep switching it around, a super lightweight booster may suit you best. However, a heavier seat is likely to feel more sturdy, be roomier and offer more comfort, and possibly offer more extended safety features.

Portability – Is there a carry handle? This might be important if you will be moving around a lot. Some seats also fold, which might be useful if you need to stash it in the boot or take it on holiday.

Ease of installation – Once you’ve done it a couple of times, installing your car seat should be a quick process. Read the instructions thoroughly, as each car seat will be different. If you are using only a seat belt, then make sure the seat feels secure and doesn’t wobble or move around.

Comfort – A comfy seat generally means a happier child, especially on long journeys, so remember to think about things like padding and cushioning. Some seats are wider for comfort, but may be harder to fit in your car, especially if you need 3 seats in a row. Is there a ventilation system for hot days? Will the headrest be comfortable? Will the seat suit taller kids?

Coverings – If you’d like the option to wash messy covers, look for covers that remove, so you can put them in the washing machine, rather than simply sponge. Don’t forget fabric finish – a natural bamboo cover might be less sweaty, for example. And is there a choice of colours?

Extra functions/details – Some car seats have additional features like cup holders, in-built headrest speakers and so on. A seat with lots of headrest/recline positions or designed for comfortable sleeping may be particularly important for you, for example.

Price – Car seats can vary wildly in price depending on their features, fabrics and accessories, but most of the ones on our list are between £100 and £250. A higher price point doesn't necessarily mean a safer or more secure seat, but some seats have been tested beyond the legal requirements for extra reassurance and these often come at a premium because those tests are expensive to perform.

Here are the best child car seats from 4 years

1. Britax Römer Kidfix i-Size, £239

– Best for abdominal support

Britax Romer Kidfix i-Size car seat

Suitable for: 15-36kg/height 100-150cm | Weight: 6.7kg | Dimensions: H63-83cm x W48cm x D42cm | i-Size: Yes | Installation: Isofix or car seatbelt | Recline positions: No | Headrest positions: Up to height 83cm | ADAC test: 1.8 (good)

This high-back booster is made in Germany by Britax, who are masters in safety and have 50 years of research and experience behind them. This is a brilliant all-round booster seat that features a whole host of excellent features including ventilation panels, removable fabrics, and advanced side impact protection. It can also be fitted either using Isofix connectors or your vehicle's seatbelt.

Its standout feature, though, is its innovative lap belt rest, which sits just in the optimal position across your child’s pelvic bone. The smart SecureGuard system fits between your child’s legs, and effectively adds a 4th contact point to a 3-point seatbelt. The result: it keeps kids’ abdomens better protected.

That’s not the only added safety feature here. There’s a shock-absorbing foam pad over the chest too, which reduces the impact of any jerky head movements. These features of the Kidfix really reassured parent tester Cali, who said, "I was really nervous moving from a harness seat but this one has a foam pad for the seat belt to help protect the neck and chest and a bit to keep the seat belt from digging into the abdomen and side-impact protection."

Pros: Comfortable for child, washable covers, advanced side-impact protection
Cons: Doesn’t recline, expensive

Available from: Boots and John Lewis

2. BeSafe iZi Flex Fix iSize, £219

– Best for small spaces

BeSafe iZi Flex Fix iSize

Suitable for: 15-36kg/height 100-150cm | Weight: 7kg | Dimensions: H64-82cm x W44-52cm x D42cm | i-Size: Yes | Installation: Integrated Isofix connectors or car seatbelt | Recline positions: 2 | Headrest positions: 14 | ADAC test: 1.9 (good)

If you’ve 2 or 3 kids, you’ll want a seat that fits 3 in the back – and this seat fits the bill brilliantly (the detachable bumpers come off). It’s designed to be ultra-slim so your child won’t feel wedged in or claustrophobic, and it's good if you’re generally squeezed for space in the back.

Reviewer Anna, who used it with her 5-year-old daughter, loved how easy it was to use. “The seat has clear guides, and the diagonal strap is held in place,” she said. She liked the lap clip that keeps the lap belt in place, and the extra pad that goes high across your child’s chest.

When it comes to safety, BeSafe’s name should be a clue as to how seriously they take it. It meets the latest R129 regulations (in fact, it was the first Group 2/3 seat ever to do so) thanks to its SIP+ extra side-impact protection.

In all, Anna felt this was a sturdy seat for a high-back booster, which do tend to feel more lightweight than seats for younger children. She found it slightly tricky to fit, but once in place it felt sturdy.

It’s comfy too, growing with your child – its highest seat position is 82cm. Plus the shaped headrest is designed for naps, and adjusts via a lever to reach its max height.

Pros: Slimline, carry handle, great quality, side-impact protection
Cons: Seats not removable to wash, expensive

Read the full MadeForMums BeSafe iZi Flex Fix i-Size car seat review

Available from: Pramworld and Natural Baby Shower

3. Nuna Aace LX, £220

– Best for growing with your child

Nuna Aace LX car seat i-Size for children 4 and up

Suitable for: Height 100-150cm | Weight: 6.7kg | Dimensions: H64-85cm x W45-57cm x D43-70cm | i-Size: Yes | Installation: Isofix or car seatbelt | Recline positions: Customisable | Headrest positions: 17 | ADAC test: 1.9 (good)

When it comes to customisable comfort, it’s hard to beat the Nuna Aace LX. Featuring no fewer than 17 headrest positions, adjustable seat depth and custom-fit recline positions, this great-looking seat is designed with comfort in mind, whatever the age and size of your child. It’s part of the Aace LX’s 3D growth system, where you can easily (1-handed in most cases) increase the seat depth and raise the headrest to provide more shoulder width for your child as they grow from 4 to 12.

If you're looking for a simple, easy to use car seat, this one is a doddle to install thanks to the Isofix fitting. It also features a green belt path with belt positioner, to help ensure your child is strapped in safely and securely.

When it comes to safety the seat really shines, with energy-absorbing EPP foam and the detachable side-impact pods helping to reduce the force of impact in a collision. This is reflected in its good ADAC rating. Finally, we love how you can remove the covers for machine washing – always a bonus with messy children in the back.

Pros: 17 headrest positions for comfort, adjustable seat depth, stylish, machine washable covers
Cons: Expensive, can take up a lot of room on its widest/deepest settings

Available from: Boots and Nuna

4. Joie i-Trillo, £75

– Best budget buy

Joie i-Trillo car seat for child 4 and up

Suitable for: Height 100-150cm | Weight: 4.43kg | Dimensions: H62-83cm x W48-56cm x D40cm | i-Size: Yes | Installation: Car seatbelt | Recline positions: No | Headrest positions: 10 | ADAC test: 2.1 (good)

If you’re looking for a reliable seat at a competitive price, this seat comes in under £100 but gives you the reassurance of having performed very well in ADAC testing. The i-Trillo has Joie's Guard Surround Safety panels for extra protection at the sides, as well as side wings and adjustable head support.

The seat is fitted using the car seatbelt, and thanks to its streamlined size it’s possible to fit 3 seats in a row in i-Size approved vehicles, with children up to 135cm in height.

We love that the Shell Grey colourway is made with 100% recycled fabrics (using 24 plastic bottles). However, the biggest hit with children is likely to be the 2 retractable cup holders, which tuck neatly away into the seat base until needed. Perfect for holding cups as well as the random little treasures children tend to collect along the way.

Pros: Affordable, Shell Grey version made using recycled materials, 2 retractable cup holders, machine washable covers, side-impact protection
Cons: Doesn't recline, not as padded as other car seats, not Isofix compatible

Available from: Joie, Halfords, Argos and Mamas & Papas

5. Maxi-Cosi Rodifix Pro² i-Size, £169.99

— Best for innovation

Maxi-Cosi Rodifix Pro2 product shot

Suitable for: 15-36kg/height 100cm-150cm | Weight: 6.24kg |Dimensions: H73-79cm x W44-51cm x D42cm | i-Size: Yes | Installation: Isofix and car seatbelt | Recline positions: 3 | Headrest positions: Up to height 79cm | ADAC test: Not tested

Around since the 1980s, Maxi-Cosi is a respected name in car seats, and this high-backed booster – an updated version of the popular Rodifix Pro i-Size – is packed with innovative features to provide a safe ride for your child.

There are numerous safety features including G-CELL side impact protection (a built-in guard to provide maximum protection in an accident) and an ultra-padded headrest to help reassure parents. We particularly rate the patented AirProtect headrest, which is designed to offer extra protection, reducing the risk of head or neck injury by 20%.

The Rodifix Pro² is intended to grow with your child and the adjustable design means the seat grows both in height and width with a press of a button on the back of the headrest. The expanding side wings make this a really comfy choice for growing kids, as does the premium Eco-Care fabrics (made from 100% recycled materials), 3 recline positions and ClimaFlow technology to keep them at the perfect temperature whatever the weather.

Easy to install using Isofix or a seatbelt, it's also lightweight enough to move between cars when you need to. While the lack of arm rests may be an issue for some parents or children, it does make it easy for an older, more independent child to buckle themselves in safely and quickly.

All in all, we think this is an excellent choice if safety and comfort are your priorities.

Pros: Fabric made using recycled materials, extra padding for safety and comfort, side-impact protection, choice of recline positions, grows in height and width
Cons: No cupholder, no arm rests, not ADAC tested

Available from: Maxi-Cosi, Natural Baby Shower and John Lewis

6. Cybex Solution T i-Fix, £174.95

– Best for naps on the go


Suitable for: 15-50kg/height 100cm-150cm | Weight: 7.2kg |Dimensions: H62.5-80cm x W50.5cm x D39cm | i-Size: Yes | Installation: Isofix and car seatbelt | Recline positions: Yes | Headrest positions: Up to height 82cm | ADAC test: 2.0 (good)

Snoozing in the car is a given for children, and the Cybex Solution T i-Fix has a patented headrest design to stop little heads tipping forward while sleeping. This not only offers comfort and safety during naps but keeps heads in a secure position when they're awake too.

This high-back booster seat has a high overall ADAC rating, showing that it should offer excellent protection in a crash. It also offers advanced linear side-impact protection.

The Cybex Solution T i-Fix is simple to install using either Isofix or a seatbelt, although weighing in at over 7kg it’s not the most lightweight model to be switching between cars.

As well as looking great, this car seat is designed for comfort, featuring a clever 3D net structure and mesh inserts to improve air ventilation and keep your child at a perfect temperature.

Plus, this easily adjusts in height and width, even with 1 hand – ideal when you have a shopping bag in the other – and will grow effortlessly with your child. It has an impressive 12 positions, so this seat really should last the distance from young child to pre-teen. And the covers can be washed to boot.

Pros: Very safe, one-hand adjustment for height and width, tilting headrest, washable covers
Cons: Cup holder needs to be bought separately, on the pricey side

Available from: John Lewis, Natural Baby Shower and Cybex

7. Graco Junior Maxi i-Size, £50

– Best lightweight car seat

Graco Junior Maci iSize car seat

Suitable for: Height 100cm-150cm | Weight: 3.4kg | Dimensions: H60.5-81.5cm x W45.6cm x D39cm | i-Size: Yes | Installation: Car seatbelt | Recline positions: No | Headrest positions: 10 height settings | ADAC test: Not tested

Packing in plenty of features at a fantastic price tag, the Graco Junior Maxi i-Size car seat is a great value choice for those on a budget. With advanced side-impact protection, this R129 i-Size car seat still offers all the safety features you’d expect and is suitable to use from around 3 to 12 years, with the 10-position headrest making it easy to adjust to your growing child.

While it isn’t Isofix compatible, the Junior Maxi car seat features open-loop belt guides to make sure the seatbelt is positioned correctly, and your child is securely strapped in.

What really impresses is how light the seat is, weighing just 3.4kg – making it an excellent option for those looking for a car seat that can be moved between vehicles quickly and easily.

It may not look as premium as other car seats in our round up, however the Junior Maxi is still nicely padded – with machine-washable covers for easy clean-ups – and includes 2 retractable cup holders to keep drinks and snacks close at hand on long journeys.

Pros: Affordable, side-impact protection, retractable cup holders, lightweight
Cons: Arms rests aren't padded, no Isofix installation, not ADAC tested

Read our full MFM Graco Junior Maxi i-Size car seat review

Available from: Halfords, Smyths Toys and Graco

8. Silver Cross Discover i-Size, £175

– Best for changing temperatures

Silver Cross Discover i-Size car seat for child 4 and up

Suitable for: Height 100cm-150cm | Weight: 7.1kg | Dimensions: H66-81cm x W46-57cm x D31cm | i-Size: Yes| Installation: Isofix and car seatbelt | Recline positions: 4 | Headrest positions: 10 | ADAC test: Not tested

Silver Cross is known for making performance products with a heritage twist, and the Discover i-Size does not disappoint with its premium, diamond-stitched embossed, eco-fabric (made from recycled plastic bottles) seat in 4 chic colourways.

However, it isn’t just about style. This high-back booster seat is generously padded, providing serious comfort for your child, as well as being easy to install, using either Isofix or your car seatbelt. The bamboo fabric gets another tick, offering temperature-regulating qualities that work brilliantly all year round.

With 10 headrest and 4 recline positions, as well as additional thigh support and removeable side wings, the Discover i-Size is designed to grow with your child. While the compact footprint is handy if you need to fit multiple seats in your car, it does mean the seat may be on the snug side for children on a higher percentile.

If you find car seats fiddly to fit, Silver Cross has you covered with its app, which takes you through the installation process step by step.

Pros: Looks good, lightweight, bamboo covers, app for easy fixing, side-impact protection system
Cons: On the pricey side, no cup holder, not ADAC tested

Available from: Silver Cross, Amazon and John Lewis

9. Cybex Solution G i-Fix, £154.95

– Best for comfort

Cybex Solution G iFix car seat

Suitable for: 15-50kg/height 100cm-150cm | Weight: 7.45kg | Dimensions: H59-81cm x W59.5cm x D40.5cm | i-Size: Yes | Installation: Isofix and car seatbelt | Recline positions: 3 | Headrest positions: Up to height 81cm | ADAC test: 1.7 (Good)

Cybex are renowned for producing excellent quality, stylish car seats with reassuring safety features. The Solution G i-Fix is no exception – this high-back booster seat features a linear side-impact protection system, as well as Cybex’s patented 3-position reclining headrest, keeping your child’s head in the seat’s protected zone even if they nod off.

As well as safety, the G i-Fix is all about comfort, thanks to the innovative 3D mesh material that will help with air ventilation whatever the temperature. The breathable fabric is soft and can also be washed in the machine when you need to tackle those inevitable spillages.

The adjustable headrest and flexible exterior wings can easily be increased in height to keep up with your growing child, while the recline function can be operated with one hand. It’s also nice and straightforward to install, using either the Isofix connectors or your car seatbelt.

Pros: Headrest recline, comfy for child, breathable fabrics, machine-washable covers, side-impact protection, 1-hand adjustment
Cons: Cup holder needs to be bought separately

Read our full MFM Cybex Solution G i-Fix car seat review

Available from: John Lewis and Cybex

10. Joie i-Traver, £135

– Best for simple installation

Joie i-Traver car seat for child age 4 and up

Suitable for: Height 100cm-150cm | Weight: 5.6kg | Dimensions: H63-83cm x W56cm x D40-44cm | i-Size: Yes | Installation: Isofix or car seatbelt | Recline positions: 2 | Headrest positions: 10 height settings | ADAC test: 1.9 (Good)

Despite its plush, heavily padded appearance, the i-Traver car seat is actually a great lightweight choice for swapping between cars, coming in at just 5.6kg. The deluxe cushioning and padded arm rest ensure it’s a comfy ride for children, but it’s certainly not style over substance here.

The i-Traver boasts some fantastic safety features – reflected in its ADAC test score – including extra side-impact protection courtesy of the Guard Surround Safety panels, cocooning headrest and cushioning memory foam layers.

The 10-height headrest can be adjusted with 1 hand (conveniently, even when the seat is installed in the car) and the 3-position seat depth helps to provide more space after those growth spurts.

Whether you plan on keeping the car seat in one vehicle or swapping, installation is nice and easy using either the Isofix connectors or your car seatbelt. The belt guides are clearly marked in green so you know exactly where the seatbelt needs to go to keep your child safely strapped in.

Pros: Adjustable seat depth, side-impact protection, extra-padded headrest, machine-washable covers, lightweight
Cons: No cup holder

Available from: John Lewis, Halfords and Mamas & Papas




Sarah has worked as a writer for over 15 years, writing about parenting for Family Traveller, Baby magazine and 5 Minute Fun, MadeForMums and The Independent’s IndyBest.