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Best child car seats and high back boosters for kids aged 3 to 12

Need a car seat for a child aged three to 12? After months of in-depth testing by parents, we reveal the best high back booster seats for kids.

By Laura Westerman | Last updated May 17, 2023

child in high back booster seat Mumsnet Best

Prices and availability checked and updated by MNHQ on 16 March, 2023.

When your child has grown out of their toddler car seat and is almost ready for school, choosing the best child car seat to see them through childhood can seem like a daunting task. After all, how can you pick a car seat for your pre-schooler that will also keep them safe through to secondary school?

We've done the research and testing, we've consulted the Mumsnet forums for recommendations and have narrowed down our picks to help you make that all-important decision. But first, some important information on the main types of car seats on offer for older kids.

What is a high back booster seat?

A high back booster is a child car seat used from approximately age three to 12. It has sides (usually well-padded) and a headrest, and it will provide routing for the shoulder and lap part of the vehicle's seatbelt. Depending on the specific seat and the car it's fitted in, it can often be used in combination with ISOFIX fixings.

What is a backless booster seat and is it safe?

A backless booster seat is a seat cushion for children that can be routed into the car using only the lap part of the seatbelt.

Legislation around high back booster seats and booster cushions changed in March 2017. An amendment to R44/04 means that backless booster seats approved after this date can only be used with children weighing more than 22kg and who are taller than 125cm.

If a booster cushion was approved before this amendment, the approval relates to Group 2/3 (15 to 36kg) seats. As such, if the label on the booster cushion has a stated weight of 15kg to 36kg, it's still legal to use.

However, as Jan James from Good Egg Car Safety points out, booster cushions are unable to provide the side impact protection that a high back booster can. As such, it's recommend that parents use a high back booster instead.

We also have Mumsnet guides to the best baby car seats, the best toddler car seats, and the best 360 car seats. If you need to kit out your car with kid-friendly accessories, we have a handy roundup of the best car sunshades for babies

Best child car seats and high back boosters at a glance

1. Best overall child car seat: Maxi-Cosi Kore i-Size

maxi cosi kore i-size car seat

Price: RRP £199.99 | Latest deals from John Lewis

Tested by parents: Maxi-Cosi Kore i-Size full review

Key specs

Age range: Approximately three-and-a-half to 12 years; 100 to 150cm | Safety credentials: Complies with ECE R129/03; Side Protection System Plus (SPS) | Fixing system: Three-point seatbelt and ISOFIX or seatbelt only | Dimensions: 51 × 44 × 76cm | Weight: 5.9kg | Guarantee: Lifetime

What we love

  • Conforms to the R129 car seat safety regulations and fits any car with ISOFIX
  • Quick and easy to fit – it took our tester a matter of minutes
  • Width of the seat increases with the height of headrest
  • Open design makes it easy for your child to get in and out
  • Lifetime warranty covers all manufacturing defects

What to know

  • ISOFIX connectors feel a little stiff at first
  • Only available in plain colours

Our verdict

Packed full of safety features, including Side Protection System Plus (SPS), the Maxi-Cosi Kore i-Size is a reliable and comfortable seat for a growing child.

As well as boasting top-notch safety credentials, the Kore's sleek design means that it should continue to appeal to your child as they get older. It looks and feels more expensive than it is, and it’s also easy to clean – crucial in a seat that will last for multiple years.

Although we found the ISOFIX connectors stiff to use at first, the Kore is both simple to use and install. Conforming to the new R129 regulations, the only other seat we tested to do this was the much more expensive BeSafe iZi Flex Fix i-Size.

Maxi-Cosi's lifetime warranty is also something none of the other manufacturers offer – and is definitely something to bear in mind when considering the car seat's longevity.

While we also tested and liked the Maxi-Cosi Kore Pro i-Size, an updated version of the Kore i-Size which has additional features and premium bamboo fabrics, we felt the value and the simplicity of the Kore (often a benefit when it comes to car seats!) was something not to be ignored.

Read next: The Mumsnet guide to the best baby car seats to buy

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2. Best budget child car seat: Cozy N Safe Augusta EZFix

cozy n safe augusta car seat

Price: RRP £80 | Latest deals from Amazon

Tested by parents: Cozy N Safe Augusta EZFix full review

Key specs

Age range: 3 to 12 ; Group 2/3 | Safety credentials: R44/04 compliant | Fixing system: Seatbelt and ISOFIX or three-point seatbelt only | Dimensions: 68 × 44 × 46cm | Weight: 4.9kg | Guarantee: 12-month warranty

What we love

  • Very simple to install
  • Lightweight at less than 5kg
  • Adjustable headrest
  • Covers very easy to remove
  • Great value for money

What to know

  • Basic, no-frills design
  • Headrest can be tricky to alter
  • Covers not machine-washable

Our verdict

Being a parent is expensive, so if you’re looking for a safe, comfortable and good-looking seat that won’t break the bank, the new Cozy N Safe Augusta EZFix could well be the answer.

The lowest priced seat that we tested, the Augusta EZFix, like its competitors, can be installed using ISOFIX. It also features armrests, deep seat padding and reversible covers to keep your small passenger happy and your car completely stain-free.

We do wish the headrest was generally easier to adjust, but this is a minor downside to an otherwise high-performing, great value seat. At less than £100, you can't really go wrong.

Read next: The best toddler car seats, according to parents

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3. Best versatile child car seat: BeSafe iZi Flex Fix i-Size

besafe izi flex fix i-size car seat

Price: RRP £259 | Latest deals from Demon Tweeks (formerly Uber Kids)

Tested by parents: BeSafe iZi Flex Fix i-Size full review

Key specs

Age range: Three-and-a-half to 12 years; 100 to 150cm | Safety credentials: Conforms to R129; ADAC rated 'Good' (1.9); Side Impact Protection Plus (SIP+); PAD+ | Fixing system: Seatbelt and ISOFIX or three-point seatbelt only | Dimensions: 42 × 52 × 64cm (in lowest position and including SIP bumpers); width without SIP bumpers: 44cm; seat height in highest position: 82cm | Weight: 7kg | Guarantee: Two years

What we love

  • Conforms to R129 safety regulations
  • Has a recline function, which is great for longer journeys
  • Boasts lots of safety features, including PAD+ for additional chin and chest protection
  • Slim design but still with plenty of space for a growing child
  • Adapt so that parents can fit three car seats in a row

What to know

  • The covers are a bit tricky to put back on after washing
  • Can be pricey (so do shop around)

What Mumsnet users say

"Try the Besafe izi flex fix. You can take the side wings off if it's in the middle. Very good safety ratings too" - recommended by Mumsnet user, elrider 

Trying to squeeze three car seats into the back of the car? The slim design of the BeSafe iZi Flex Fix i-Size is ideal for families who need a bit more flexibility day-to-day.

We love the fact that the manufacturer has really considered what parents need when designing this seat. With children required by law to use a car seat or booster until they are 12 years old or 135cm (whichever comes first), it can often be tricky to find a configuration of seats to fit a packed family car. The versatility of the iZi Flex Fix means this is much easier to accomplish.

But it's not just the seat's versatility that impressed us. Like the Maxi-Cosi Kore i-Size, the iZi Flex Fix conforms to the latest R129 regulations, but, unlike our overall winner, it's also equipped with three (yes, three!) layers of Side Impact Protection for maximum safety and comfort.

Yes, it may be pricey for parents on tighter budgets, but we think the BeSafe iZi Flex Fix i-Size is nevertheless a great choice for busy families.

Read next: The best car sunshades for babies

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4. Best child car seat for ease of use: Britax Römer Kidfix III M

britax romer kidfix car seat

Price: RRP £189 | Latest deals from Demon Tweeks

Tested by parents: Britax Römer Kidfix III M full review

Key specs

Age range: 15 to 36kg; Group 2/3 | Safety credentials: Conforms to R44/04; ADAC 'Good' (1.7); OAMTC 'Good'; Stiftung Warentest 2019 'Best in Test'; SecureGuard; Advanced Side Impact Protection | Fixing system: Three-point seatbelt and ISOFIX or three-point seatbelt only | Dimensions: 67 to 45 × 54 × 43cm | Weight: 7.5 kg | Guarantee: Two years

What we love

  • Installation takes approximately five minutes
  • Headrest simple to adjust for different heights
  • Longer seating area means added comfort for even the tallest of children
  • V-shaped backrest grows with your child
  • Excellent safety credentials

What to know

  • May be tricky for a child to strap themselves in if there are three seats installed in a row
  • Bulky and heavy

What Mumsnet users say

“We've got the Kidfix and it is v.good - would recommend. Solid as a rock and doesn't move around at all” - recommended by Mumsnet user, fabhead

Our verdict

A breeze to operate in an ISOFIX-ready or seatbelt-only car, the Britax Römer Kidfix III M is our top pick for ease of use.

Everything about this seat is simple, whether that’s installing the seat in your car, adjusting the ergonomic headrest or removing, washing and replacing the covers. It’s really comfortable too, which is crucial considering how long you'd need the seat to last.

While it is one of the bulkiest seats we tested and too heavy to lift between cars, if you’re looking for a seat that ticks all the boxes when it comes to safety, style and practicality, then the Britax Romer Kidfix II M is an excellent choice.

Key features also include a large seating area, a V-shaped backrest that grows with your child, and SecureGuard and Side Impact Cushion Technology (SICT) for extra protection in the event of a collision.

Read next: The best pushchairs to buy, as tested by parents

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5. Best lightweight child car seat: Apramo Ostara Fix

apramo ostara fix car seat

Price: RRP £89 | Latest deals from Amazon

Tested by parents: Apramo Ostara Fix full review

Key specs

Age range: 15 to 36kg; Group 2/3 | Safety credentials: Conforms to ECE R44/04; Superior Side Impact Protection (SSIP) | Fixing system: Three-point seatbelt and ISOFIX or seatbelt only | Dimensions: 73 × 48.5 × 48cm | Weight: 5.5kg

What to love

  • Lightweight – good for on the move
  • Easy and quick to install
  • Simple design
  • Seat covers easy to remove

What to know

  • Headrest difficult to adjust
  • Fabric could be irritating to sensitive skin

Our verdict

If you’re a family that likes to travel, or if you need to transfer a seat from car to car, then the lightweight Apramo Ostara Fix may be right up your street.

Heavily padded around the head, sides and hips to keep your child secure and comfy at all times, the Ostara Fix also has Superior Side Impact Protection, providing extra cushioning in the event of a side collision.

At just 5.5kg, it gives you the option of taking your own car seat with you when you travel, and is ideal if you plan to use your seat in multiple cars – it's light enough to make installation that much less of a chore.

The only downside is the headrest which was tricky to adjust despite boasting seven different settings, however we love how easy the seat is to clean – and its price tag is a bit of a boon too.

Read next: The best lightweight strollers to buy

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6. Best child car seat for long car journeys: Diono Everett NXT

diono everett car seat

Price: RRP £100 | Latest deals from eBay 

Key specs

Age range: 15 to 36kg; Group 2/3 | Safety credentials: R44/04 compliant | Fixing system: Belted and ISOFIX or three-point seatbelt only | Dimensions: 72 × 46 × 41cm | Weight: 4kg | Guarantee: 12 months

What we love

  • Lightweight so great for travelling
  • Cushioned headrest with Side Impact Protection
  • Memory foam support cushions for extra comfort
  • Great price

What to know

  • Headrest difficult to adjust
  • Our tester felt there was a slight wobble when using ISOFIX (without a child in the seat)

Our verdict

The Diono Everett is the ideal car seat for travelling. At just 4kg, it's lighter than both the Cozy N Safe Augusta EZFix and the Apramo Ostara Fix, but didn't perform as well during testing, particularly when it came to adjustments and overall stability.

It is great value though, offering an ISOFIX option despite its budget-friendly price tag, with lots of padding designed for maximum comfort and covers that are easy to remove, machine-wash and refit. Our tester also found it easy to install.

Read next: The best bike trailers to buy

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7. Best child car seat for comfort: Maxi-Cosi Kore Pro i-Size

maxi cosi kore pro i-size car seat

Price: RRP £199.99 | Latest deals from John Lewis 

Key specs

Age range: 100 to 150cm | Safety credentials: Complies with ECE R129/03; Side Protection System Plus (SPS) | Fixing system: Seatbelt and ISOFIX or three-point seatbelt only | Dimensions: 51 × 44 × 76cm | Weight: 6kg | Guarantee: Lifetime

Pros ·

  • Conforms to R129
  • ClickAssist light for easy buckling in
  • Bamboo fabric covers
  • Simple installation
  • Lifetime warranty covers all manufacturing defects

Cons

  • ISOFIX connectors feel a little stiff at first
  • More expensive than the Maxi-Cosi Kore i-Size – our tester thought the ClickAssist light wasn't worth the extra cost

Our verdict

Maxi-Cosi's Kore Pro i-Size has all the safety and comfort of the Maxi-Cosi Kore, but boasts additional features, including a ClickAssist light.

This is an innovative addition that our tester and her daughter really enjoyed. The light illuminates the seatbelt socket for 30 seconds once a child is in the seat, which helps them to buckle themselves in, even in the dark.

In contrast to the regular Kore, the Kore Pro's covers are made from premium bamboo fabrics to keep a child cool in warmer weather.

Read next: The best baby carriers to buy

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What are the different types of child car seats?

UK law states that all children need to be in a car seat up to the age of 12 or 135cm (whichever comes first). When buying a seat at this stage, ideally you'll want it to last until your child no longer needs one.

Child car seats fall into five groups:

Group 1/2/3 (R44/04) – from 9 to 36kg, or around nine months to age 12 (or 135cm)

Group 2 (R44/04) – suitable from 15kg to 25kg, or approximately four to six years of age

Group 2/3 (R44/04) – from approximately four years up to age 12 or 135cm (15 to 36kg)

Group 3 (R44/04) – can be used with children who weigh 22kg to 36 kg and are 125cm or taller

i-Size (R129) – conforming to the R129 regulation, i-Size car seats for this age group can be used from 100 to 135cm (or from 135cm to 150cm in specific cars)

Read next: Tips on keeping your family safe on the road

What is i-Size?

i-Size car seats meet the new R129 European car seat safety standards that came into force in July 2013, which aims to increase the safety performance of all car seats on the market.

R129 regulations are currently running in parallel with R44 so you can buy car seats that adhere to either guidelines. At some point, R44 car seats will be phased out of the shops – but it's unclear exactly when this will happen.

Read next: Our guide to UK car seat regulations

What are the differences between R44 and R129?

R44

  • 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

  • Classification is based on height
  • Rear, front and side-impact testing
  • Seat is attached using ISOFIX points
  • Seat must be rear-facing until your child is older than 15 months

How much should I spend on a car seat?

Prices vary considerably and it is worth looking into exactly what higher-priced seats are offering before spending any money as the most expensive seats aren’t necessarily the best.

Safety is the most important thing and all car seats must conform to R44 or R129 regulations. Bigger brands often conduct their own safety testing too.

So, if you’re on a tight budget, do keep safety in mind as your first priority and make sure you always check independent reviews before buying.

Read next: The best 360 car seats to buy, as recommended by Mumsnetters

Can you use secondhand car seats?

A car seat's main job is to protect your child 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 secondhand 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.

As such, experts from Good Egg Car Safety recommend never buying a secondhand car seat.

How we tested our selection of child car seats

Our tester, Jemma, used the child car seats we tested exactly as any mum would. They were tested right from the very start – from the unpacking and assembly of the seat when it arrived to installing it into the car.

Each seat was used on the daily school run and on longer trips of up to an hour. They were also switched between cars and different-aged children before being scored on other practicalities like stain removal, washing and getting pesky covers off and back on again.

Here's what we looked at for each of the six key testing criteria.

Safety, stability and comfort

  • Crash test results
  • How easy was the seat to install – was there any room for error?
  • Additional safety features
  • Materials – are they durable and robust?
  • How comfortable was the child in the seat?
  • Was there anything about the seat that could distract the parent while driving?

Assembly

  • Were clear instructions provided?
  • Was everything needed for set-up included in the box?
  • Did the seat need more than one person to install it?
  • Was the seat easy to install overall?
  • Were there a website and a customer service helpline if you got stuck?

Day-to-day use

  • Could the child get in and out of the seat quickly and safely?
  • For longevity – could the seat grow with a child?
  • Was it easy to adjust the seat if you needed to use it with a child of different ages?
  • Was it easy to strap your child in the seat when you were in a rush? Could they do it themselves?

Aesthetics and cleanliness

  • Was the seat easy to clean? We spilled milk and juice on each seat to see how it fared after cleaning
  • Were the covers removable for washing, and were they easy to put back on afterwards?
  • How does the seat look overall? Is the fabric good quality? Would the seat still appeal to your child as they grow?

Value for money

  • Does the seat offer good value for money?
  • Does the price seem reasonable, particularly given the length of time it will be used?

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We spend hours researching, speaking to parents, analysing data and listening to experts before we test out the products on our shortlist.

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We do sometimes earn revenue through affiliate (click-to-buy) links in our articles. This helps us fund more helpful and independent review pieces like this one. However, we never allow this to influence our coverage.

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