Updated 25 March 2022
Is your child big enough to begin sitting facing forward in the car? Children should continue to use a car seat for as long as possible, even facing forward. We tested high-backed booster seats and name the Maxi-Cosi Rodifix AirProtect as our best in test. This is a spacious car seat that’s comfortable even for larger children, and which can be reclined into a resting position.
Our best premium choice is the BeSafe iZi Flex FIX i-Size. This high quality and adaptable booster seat has a reclining position, spacious seat area and intelligent side impact protection.
Our tests are independently conducted and reflect the test editor's honest and objective opinions. Selection of products and test results are in no way influenced by manufacturers, retailers or other internal or external parties.
We carry out our tests ourselves and test all products as they are intended to be used. This test focuses on the child’s comfort, product flexibility, the functions you get for your money and how long the seat can be used for. We didn’t test safety, but all high-backed booster seats in the test are type approved and tested according to European regulations.
In our tests of booster seats, we asked normal families with children of different ages to test the car seats as part of their normal everyday activities. The seats were used with different types of cars and over a longer period to get an idea of how durable they are. The dimensions we state in the test should be seen as a comparison between the different models of car seat and not as an indication of how well a child of a certain length will fit into the seat. During the tests, we looked in detail at aspects including:
Sitting comfort: Is the car seat comfortable for the child to sit in, are there any functions to make things easier if the child falls asleep, and how well-padded is the cover?
Functions: Is it easy to adjust the height of the headrest and back, is there any extra built-in impact protection, and is the cover easy to remove for washing?
Use: What’s it like to install the booster seat, is it easy to use the seatbelt when the child sitting in the seat, and is the seatbelt at the right height on the child’s body?
Our testers’ assessments of the booster seats are then compared to their price, which forms the basis for the final score. Compare prices for all high-backed booster seats on PriceRunner.
Popular booster seat with long period of use and high comfort levels
Type of seat: Isofix Age of child: 4-12 years Weight of child: 15-36 kg Seatbelt horns: No Seatbelt guides at shoulder: Has automatic closure Weight: 4.9 kg Width: 55 cm Back support height min-max: 70-88 cm Reclining position: Yes
The Maxi-Cosi Rodifix AirProtect is the latest update from the popular and very good value brand that’s occupied a space in many thousands of back seats over the years. It’s impressive to see how many functions come with this model, particularly given the Maxi-Cosi Rodifix AirProtect's reasonable price tag. The car seat can be used both with and without Isofix brackets, and just like other high-backed booster seats using Isofix, it’s important to keep the car seat firmly attached even when no child is occupying it. This is to avoid the car seat from becoming a safety risk in the case of a collision.
On the Maxi-Cosi Rodifix AirProtect, the seatbelt guides, which close automatically once you’ve inserted the seatbelt, are clearly marked on both sides of the headrest. This means the car seat can easily be placed on all seats in the car. But remember that children shorter than 140 cm shouldn’t sit where there’s an active air bag! Because the Maxi-Cosi Rodifix AirProtect has no seatbelt horns for the hip belt, it’s also important that before setting off an adult double checks that the hip belt is at the right position and not over the child’s stomach.
It’s easy to adjust the height of the back support by pressing in a small but visible button at the top of the headrest. This undoes the catch and the car seat can then be adjusted upwards or downwards to fit the height of the child. The operation is convenient and it only takes seconds to move between different positions, which means that the high-backed booster seat is ideal for families with children of different heights taking turns to use the Maxi-Cosi Rodifix AirProtect.
One function that was very popular with the families who tested the Maxi-Cosi Rodifix AirProtect is that the design of the booster seat’s reclining position allows the child to switch between upright sitting position and reclining position. They do this by holding the levers on either side of the seat and pulling the levers upwards. When the levers have been pulled upwards, the base of the car seat can be slid forward or backwards, and the back support changes angle accordingly. This is very practical for children who want to sleep in the car seat, because the reclining position helps prevent the child's head from tipping forward.
The Maxi-Cosi Rodifix AirProtect is generously proportioned and perceived as spacious and cosy. The children who participated in the test were between 5 and 10 years old and all of them felt that the car seat was comfortable to sit in. The older children were particularly positive about this high-backed booster seat, because it provides plenty of space for the upper body and is even suitable for children with broader shoulders. The headrest is also popular because it provides support for the head and also offers a good view out of the window. It isn’t difficult to understand why this good value car seat has become such a favourite with so many families. It quite simply provides a lot of comfort for your money and suits children of many different ages.
Flexible, safe and exclusive booster seat with extra everything
Type of seat: Isofix Age of child: 4-12 years Weight of child: 100-150 cm Seatbelt horns: No Seatbelt guides at shoulder: Has automatic closure Weight: 7.1 kg Width: 44 cm without SIP bumpers, 52 cm with Back support height min-max: 53-73 cm Reclining position: Yes, which the child can control themselves
Pronouncing the name of the BeSafe iZi Flex FIX i-Size maybe a bit complicated, but fortunately that’s the only thing that’s the slightest bit confusing about this really nice car seat. With its SIP bumpers on both sides of the car seat and its neat proportions, the iZi Flex FIX i-Size is the first booster seat to be i-Size approved, which means it passes the requirements for side impact in the case of any collision and has limited maximum dimensions. The SIP bumpers included with the car seat are uncomplicated to click into place, but it should be mentioned that without these the car seat is only 44 cm wide, which offers the amazing option of having three car seats next to each other in a normal car’s back seat.
Even with the SIP bumpers, the iZi Flex FIX i-Size is a convenient size with its neat 52 cm in width. As well as the SIP bumpers, it also comes with a SIP+ cushion, which you attach to the side of the car seat closest to the car door to provide additional side impact protection. But the safety aspects of this car seat don’t end there. PAD+, which is a protective system that prevents the child’s neck from bending too much in the case of a collision, is attached around the seatbelt, providing additional safety. However, it’s extremely important that the PAD+ is at the right position, which can seem a bit fiddly if you’re not used to it, but which our tester children learned quickly.
Another operation that requires a bit of practice is the hip belt guide, which consists of a buckle that you attach the seatbelt into. The buckle is easy to get into place because it clicks with a magnet, but for the first few times it can feel difficult to open again. The key is to pull the buckle in the right direction. Correctly tightened, the buckle does a good job – in other words makes sure the seatbelt doesn’t glide up towards the child’s stomach.
As well as being a high-backed booster seat with safety in focus, the iZi Flex FIX i-Size is a really comfortable car seat for the child. Both the back support and seat are generously dimensioned and have soft padding. The headrest is also flexible as it can be raised and lowered in several steps, and our testers particularly appreciated the fact that the control is on the side and not at the back. It’s also very easy to set the car seat for maximum comfort even if different children are using it. And as if that wasn’t enough, the car seat offers a convenient function that means the child can angle the car seat to reclining position themselves during the journey using two brackets on the sides of the base. The car seat can be used in cars both with and without Isofix points.
Even though the iZi Flex FIX i-Size has a relatively high price tag, there are good reasons for that. With its clever functions, high levels of safety and high scores in collision tests – and plenty of comfort for the child – there really isn’t much more you could ask from a high-backed booster seat. So we have no doubts about naming the iZi Flex FIX i-Size as our best premium choice.
Faithful companion with spacious design and safety focus
Type of seat: Isofix Age of child: 4-12 years Weight of child: 15-36 kg Seatbelt horns: Yes Seatbelt guides at shoulder: Has automatic closure Weight: 6.4 kg Width: 50 cm Back support height min-max: 56-74 cm Reclining position: Yes, the headrest can be angled
With its long period of use, from a weight of 15 kg up to 36 kg, the Cybex Solution S-Fix is a car seat kids will be happy to use. It offers high levels of comfort with plenty of padding in the seat area and a dirt-repellent cover that’s easy to clean without being shiny or slippery. We give extra points for the built-in holes in the cover, which create ventilation during the warmer months of the year, and the generously proportioned seat area and space for the child’s shoulders. The headrest also gets praise as it’s wide enough not to feel claustrophobic but simultaneously narrow enough not to compromise on safety.
The Cybex Solution S-Fix has a back support with a full 12 different height positions, each of which can be achieved using just one hand to adjust the back of the car seat. The manual is on the same side of the car seat in a clever space that means it’s always with the car seat and available for a new user. As well as raising or lowering the headrest, it can also be angled, which increases the child’s comfort when they need to rest during the car journey. It also makes the journey safer because the child’s head doesn’t tip forward and fall outside the safety zone.
Nor does the safety focus of this car seat end there. The Cybex Solution S-Fix is also equipped with the integrated LSP linear side impact protection system, which clicks out against the side of the car seat closest to the car door, reducing the forces of a side impact by 25%. Convenient car seat that never compromises on safety
The Cybex Solution S-Fix works with both Isofix and non-Isofix cars. It’s important to remember that if you don’t have Isofix points in your car the car seat must be attached even when it isn’t being used by a child, because otherwise the car seat can become a projectile in the case of a collision – just like other booster seats. The neat size of the car seat makes it easy to install in the car and the clever seatbelt guides make sure the seatbelt is exactly where it should be – level with the child’s shoulders.
Overall, the Cybex Solution S-Fix is a comfortable and very user-friendly high-backed booster seat that isn’t flashy but never compromises on safety. A secure companion that will be with you for a long time.
Modern car seat with a good manual and secure belt management, most suitable from the age of 7
Type of chair: Isofix Child age: 4–12 years Child weight: 15–36 kg Belt horn: Yes Belt holder at axle: Has automatic closure Weight: 6.7 kg Width: 48 cm Backrest height min-max: 55–75 cm Rest mode: No
Britax has a whole series of car seats in its Kidfix range, all of which can be fitted with isofix. However, it is not necessary to use the isofix. It prevents the chair from sliding around on the seat and eliminates the need to fasten the seat when not in use by your child. A loose seat belt can injure other passengers in the event of a collision.
Britax Kidfix i-Size is narrower than older Kidfix chairs. The 48 cm width makes it easy to fit the car seat, or to sit next to it. But that doesn't mean the car seat is small. On the contrary, Kidfix i-Size appears to work best for older children. This is because it is recommended that the child’s knees should be positioned outside of the seat area when sitting in a car seat. This is something that cannot be done if the child is shorter than 125 cm tall, and certainly not with the minimum length of 100 cm specified by Britax.
On the other hand, children taller than 125 cm that were placed in the Kidfix i-Size sat very nicely. The chair felt like it was moulded for them. On the Kidfix i-Size, the headrest has become deeper and tighter. The child is perceived to have good protection from the sides, but till has a good view out. The backrest is spacious and height-adjustable, with a lock located at the top of the headrest. However, for a 12-year-old, which is the maximum age given for the Kidfix i-Size, the car seat feels a bit tight around the shoulders.
When a child travels in a forward-facing position, it is even more important that the belt is positioned correctly around their body. Britax Kidfix i-Size greatly facilitates this. Between the child's legs there is a belt holder called SecureGuard, which prevents the belt from sliding up from the hips, against the soft parts of the stomach. The holder is well positioned. We had no complaints about it pressing against the groin or the inside of the thighs.
The chair has two protruding belt horns. Thanks to clear instructions on the sides of the chair, there was no doubt about how to pull the belt. An XP-PAD is fastened around the belt at the top of the child’s neck, reducing neck strain in the event of a collision. The chair has normal padding. Even on longer car journeys, the children who sat in it said that it was comfortable. The cover was comfortable directly against the skin and easy to wipe clean.
It is always difficult to say which car seat is best, as it depends entirely on your own vehicle and child. Britax Kidfix i-Size was not perceived to be fully compatible with children under the age of 6-7. Which is good in a way, as children should preferably sit in a rear-facing position until that age anyway.
In our experience, the Kidifx i-Size suits the ages of 7-11 best, and children of that age generally sit really well. The SecureGuard between the legs guides the belt perfectly, the belt horn also helps, and the XP-PAD, together with the side impact protection, provides that extra sense of security. This is exactly what you’d expect from a modern car seat, and Britax fully delivers with the Kidfix-i-Size.
Spacious and easy-to-use high-backed booster seat that’s especially suitable for tall children
Type of seat: Isofix Weight of child: 15-36 kg Seatbelt horns: No Seatbelt guides at shoulder: Has automatic closure Weight: 9.7 kg Width: 46 cm Reclining position: No
The Axkid Bigkid 2 is a booster seat that’s installed in the car using Isofix points. This prevents the booster seat from sliding on the car seat and means you don’t have to belt the booster in place when the child isn’t in the car. However, it is also possible to use Axkid Bigkid 2 in car seats without Isofix brackets.
Booster seats may at first glance look like the simplest car seat, which requires the least fitting. But this doesn’t mean you can choose just any model. It’s important that the high-backed booster seat is both suitable for the vehicle seat and that it’s the correct size for the child being seated in it. You need to bear this in mind before buying the Axkid Bigkid 2.
Axkid are very good at pointing out that children should sit facing backwards for as long as possible. The Bigkid 2 works well in this position. The booster seat is designed for use from 125 cm – a height that children reach on average at the age of 7. One disadvantage of Axkid Bigkid 2 is that many children who are just about to start travelling forward-facing in the car will be too small for the booster seat. For example, the seat area is too deep when we have a normal height six-year-old test the Bigkid 2.
The advantage is that Bigkid 2 has a long usage time in terms of age. The booster seat adjusts easily as your child grows. The backrest can be height adjusted with a convenient one-hand grip, and in its highest position the booster seat is spacious enough to allow a 140 cm tall 11-year-old to sit comfortably with support right out to their knees. Their shoulders don’t get pinched or squashed under the headrest.
The Axkid Bigkid 2 has a stylish appearance. The upholstery feels porous and our testers found the booster seat to be soft and comfortable. The included ASIP – the side impact protection – attaches easily to the side of the high-backed booster seat that’s closest to the car door. The Bigkid 2 has four points marked in red on the sides of the headrest and on the seat surface. These show where to run the seat belt. The belt attachment is something the Axkid Bigkid 2 is especially good at.
The red dots down by the seat show how to run the seat belt over the child’s hips. To prevent the belt from slipping upwards, the Axkid has an extra anchor point between the child's legs. The belt should pass through and be attached to this crotch strap. This eliminates the risk of the seat belt lying ib the child’s stomach, with the risk of serious injury to soft tissue in the event of a collision.
The Axkid Bigkid 2 is a very spacious and easy-to-use booster seat. If you have large or tall children, the Bigkid 2 enables a longer time in a booster seat, and the additional anchor point between the child’s legs increases confidence that the seat belt is running correctly across the child's body. Car safety is extremely important, so it’s very positive that with the Bigkid 2, Axkid are offering a high-backed booster seat that can be used for a long time.
Spacious and comfortable high-backed booster seat with clever fourth anchoring point between the legs
Type of seat: Isofix Age of child: 4-12 years Weight of child: 15-36 kg Seatbelt horns: No Seatbelt guides at shoulder: Has automatic closure Weight: 7.5 kg Width: 54 cm Back support height min-max: 57-73 cm Reclining position: No
The Britax Kidfix III M is a popular booster seat from Britax, specially designed to also suit the slightly larger child in the intended age range of 4-12 years. And Britax have definitely succeeded with this. The seat is deeper than in many other high-backed booster seats, providing good support for the child’s thighs even up to the age of 10-11.
The Kidfix III M is a booster seat that’s installed in the car using Isofix points. The Isofix arms are adjustable and it’s easy to get the car seat in place. But the Kidfix III M can just as easily be used in car seats without Isofix points. In this case, it’s important to attach the car seat with the seatbelt even when it isn’t being used by a child, because otherwise it can be projected forwards, causing injury during a collision.
Of course safety is the most important thing when it comes to car seats, and Britax do a good job of helping the user feel secure. Britax’s SICT side impact protection system can be found on both sides of the Kidfix III M. This is a round plate that you screw out on the side of the car seat that’s closest to the car door. In case of a collision the SICT absorbs some of the impact forces.
By the child’s shoulders there are seatbelt guides, and depending on where you position the Kidfix III M in the car, the seatbelt is drawn through one of these to come out at the right position and be led correctly across the child’s ribcage. The Britax Kidfix III M has no seatbelt horns, reducing the risk of the seatbelt being incorrectly placed over the hips.
What the car seat does have, however, is Britax’s SecureGuard function, which is a seat belt holder between the child’s legs. The hip belt is threaded through the SecureGuard. This creates a fourth anchor point and prevents the seatbelt from sliding up towards the child’s stomach.
It’s very important that the seatbelt stays over the hips to prevent serious internal damage in the case of a collision. The function is great, but the SecureGuard itself met with a mixed reaction from the children who tested the car seat. Some of them felt that it pinched between their legs and made the car seat uncomfortable. Others didn’t find it a problem at all.
The Britax Kidfix III M is available with a special cover with extra ventilation that’s partly made from airy mesh. And it really does seem to make a difference during long car journeys on hot summer days, without having any negative effect in the winter. This high-backed booster seat is easy to adapt to the child. You can adjust the height of the back support using just one hand. The headrest has a good design that supports the child’s head.
It’s important to allow the child to try out the Britax Kidfix III M before you buy, ideally in the car it will be used in. The deep seat means it can work less well for younger children who’ve just changed from a rear-facing car seat. But for larger children, the Britax Kidfix III M is an excellent choice to say the least.
Convenient and comfortable high-backed booster seat with built-in and really clever lighting in the sides
Type of seat: Isofix Age of child: 4-12 years Weight of child: 15-36 kg Seatbelt horns: No Seatbelt guides at shoulder: Seatbelt threaded into place Weight: 7.5 kg Width: 44 cm Back support height min-max: 55-72 cm Reclining position: No
The Maxi Cosi Kore Pro i-Size is a more advanced version of Maxi Cosi's Kore i-Size booster seat. What primarily distinguishes the models is the fact that the Kore Pro has LED lamps on the sides. The model also has a slightly better cover, with increased comfort and better ventilation in the fabric.
According to our testers, the Kore Pro is very comfortable to sit in. According to Maxi Cosi, the car seat is intended for children between 100 and 150 cm in height. However, our testers felt that for children above about 140 cm the car seat was too tight around the upper body. The width of the back support is good, but in terms of length the shoulders are starting to touch the bottom edge of the headrest. But this can vary from one child to another. If the child has longer legs but a short upper body, they will fit in the Kore Pro for longer.
Our test children appreciated the design of the seat. The headrest has a good design. The child’s head is nicely enclosed but they can still see out at the sides. When the back support is extended, the car seat also expands slightly in terms of width, which means it doesn’t feel too narrow. The way you adjust the height of the back support and headrest is extremely good.
Instead of a button in the centre of the headrest, or at the back of the car seat, the Maxi Cosi Kore Pro has a button on either side of the top edge. And you only need to push in one of the buttons for the height to be adjustable. This means it’s always easy to get at, which in turn means you more often make sure the back support is correctly adjusted for the child using the car seat.
The Maxi Cosi Kore Pro i-Size is installed in the car using Isofix brackets. The arms can be extended when the car seat is in place and are a reasonable length, so it’s easy to access the car’s Isofix points. You can also use the Kore Pro in a seat without Isofix points. If you do this, you must remember to belt the car seat in place when it isn’t in use so it doesn’t become a potentially hazardous projectile in the case of a collision.
In many ways, the Maxi Cosi Kore Pro i-Size is very similar to lots of other high-backed booster seats on the market. It’s ClickAssist Light that makes the Kore Pro stand out – and not just a little, either. The booster seat has lights on each side. About three seconds after the child has settled into the car seat, one light comes on. You can choose which side lights up depending on where in the car the car seat is and where the seatbelt buckle is positioned.
The light stays on for about 20 seconds, and is sufficiently powerful for it to be much easier to find the buckle you insert the seatbelt in. It may sound like a gimmick to have a light in a booster seat, but on dark winter mornings it’s a great help in quickly getting the child safely into the car seat. So as well as being a narrow and convenient high-backed booster seat, the Maxi Cosi Kore Pro i-Size really helps to reduce stress, at least in the darker months of the year.
Clever and convenient high-backed booster seat that can be made narrower
Type of seat: Isofix Age of child: 4-12 years Weight of child: 15-36 kg Seatbelt horns: No Seatbelt guides at shoulder: Has automatic closure Weight: 6 kg Width: 54 cm (44 cm without SIP bumpers) Back support height min-max: 55-73 cm Reclining position: No
The BeSafe iZi Flex S FIX booster seat is, both in terms of design and product name, very similar to the slightly more exclusive iZi Flex Fix i-Size model, and at a quick glance it can be difficult to tell them apart. The difference is that the iZi Flex S FIX doesn’t have all of the functions of its bigger sister, the iZi Flex FIX i-Size. For example, it’s lacking the PAD+ padding that attaches to the seatbelt. But just like the iZi Flex FIX i-Size, it’s a very easy to use and convenient high-backed booster seat with an attractive design.
You can use the car seat both with and without Isofix points, but if you use it without – just like all other car seats – it’s important to keep the car seat attached even when it isn’t being used by a child. Otherwise the car seat can become a dangerous projectile in the case of a collision. You unfold the Isofix arms by pulling on a handle on the front of the car seat's underside. On the back of the headrest there is also a clever handle that allows you to carry the car seat, and the car seat manual is stored by this handle.
The BeSafe iZi Flex S FIX is a car seat that our testers were very happy with. The car seat is very comfortable in terms of the seat, headrest and back support. The padding in the seat area is of normal thickness and didn’t cause any problems during car journeys. The cover is dirt repellent and easy to wipe off. The headrest, which BeSafe call V-shaped, is comfortable to lean the head on and offers good visibility out of the window.
One unique characteristic that the BeSafe iZi Flex S FIX shares with the iZi Flex FIX i-Size is that the car seat can be made narrower by removing the side impact protection system, which is called SIP bumpers. With these removed the car seat only measures 44 cm wide, which means you can fit as many as three car seats beside each other in a normal sized back seat. This is very practical for a family with multiple children or for car sharing.
BeSafe have thought carefully about adjusting the height of the back support. Because there’s a lever on each side of the BeSafe iZi Flex S FIX to raise and lower the back support, which spares your back as a parent, because you no longer have to tie yourself in knots in a narrow space. In other words, you only have to use one of the levers to adjust the height – which feels strange the first time you do it but is something you quickly get used to. The headrest is also easy to adjust, but make sure you check that the seatbelt is at the right height and is running freely through the car seat’s belt guides.
The seatbelt must run over the child’s hips and not over their stomach. Because the iZi Flex S FIX doesn’t have seatbelt horns, it’s important to try out the car seat and adjust the details before you start driving, which may feel a bit complicated if your car and your child aren’t fully compatible with the BeSafe iZi Flex S FIX. But if you’ve tried the car seat out in your own car and everything’s fine, the BeSafe iZi Flex S FIX is a very good value car seat that’s a great choice for a larger family where it's useful to fit several children in the back seat.
Uncomplicated high quality and comfortable booster seat
Type of seat: Isofix. Age of child: 4-12 years. Weight of child: 15-36 kg. Seatbelt horns: Yes Seatbelt guides at shoulder: Elastic catch Weight: 6.7 kg Width: 54 cm over side impact protection (retracted) Back support height min-max: 55-75 cm. Reclining position: Yes, the headrest can be angled
Cybex is a brand that offers robust quality throughout its entire range, and the Solution M-Fix booster seat is no exception. With well-sewn seams, rounded edges in the base and a memory foam-like material in the headrest, the Solution M-Fix offers high comfort levels, both for the child and for anyone sitting beside them in the back seat. The car seat feels cosy and the headrest in particular is comfortable to lean back on.
Just like the seatbelt guide at the shoulder is easy to understand, it’s also easy to extend the side impact protection on the right side of the car seat – the one closest to the car door. And it’s easy to remove the side impact protection on the side where it isn’t needed, making it more comfortable for any passenger in the adjacent seat. The cover also feels high quality, although it’s a bit fiddly to put it back on after it’s been removed for washing.
You push in a handle to adjust the height of the back support. Even if the Cybex Solution M-Fix doesn’t offer a classic reclining position, there’s a good solution in that the headrest can be adjusted to three different angles: upright, intermediate and leaning backwards. And it’s this you adjust when the child falls asleep in the car seat so their head doesn’t tip forward. This is a convenient and functional solution despite the simpler design.
With its carefully designed details, comfortable headrest and straightforward Isofix brackets, the Cybex Solution M-Fix is a simple, high standard car seat. It perhaps doesn’t stand out exactly, but at the same time the Cybex Solution M-Fix won’t disappoint and it’s a really good value high-backed booster seat.
The longer the child can travel in the car in a rear-facing seat, the better. Even for a five-year-old, it’s five times safer to travel facing backwards and forwards. But when the day comes that your child no longer fits into a rear-facing car seat, it’s time to move to a high-backed booster seat. What a booster seat does is to lift the child up in the car seat so the car seatbelt is at the right points over the child’s body – in the crease between neck and shoulder, diagonally across the rib cage and, in the case of the hip belt, should be on the child’s thighs. If the hip belt is too high up, the child risks internal injuries in the case of a collision.
The child should change to a booster seat when they exceed the length or weight limits on the rear-facing car seat, or when the upper edge of the child’s ears stick up above the car seat headrest. If the rear-facing car seat has a hard headrest, it’s the headrest height that should be the deciding factor. In rear-facing car seats with a softer cushion as a headrest, it’s the outer shell of the car seat that mustn’t be exceeded by more than one third of the head.
As well as high-backed booster seats, there are also simpler backless booster seats. These were once approved for use during the same period as a high-backed booster seat, but since 2017 newly produced backless booster seats are only approved for children over 125 cm in height and weighing at least 22 kg. Older backless booster seats are approved for use from 15 kg – the old recommendation – for a limited period only.
In the UK, children older than 12 or taller than 135 cm no longer need to use a car seat. Just like the question about when your child can start sitting facing forwards in the car, the issue of your child travelling in the car without a car seat comes down to them having reached a certain age for the body to be able to cope with the forces caused during a collision. So length and weight aren’t necessarily the most relevant factors, but at the same time it’s most important that the child is sitting safely, and if their head is above the back support (if there’s no adjustable headrest), a beltless or high-backed booster seat is no longer the safest option.
Unlike a backless booster seat, a high-backed booster seat also has built-in back and neck support. Both alternatives are equally safe, providing the seatbelt is correctly positioned. But a high-backed booster seat has the advantage that it helps keep a smaller child in the correct position. On a backless booster seat, there is a risk that the child will lean to the side when the car turns, ending up outside the protection of the seatbelt. A high-backed booster seat is also better than a backless booster seat at keeping the seatbelt in the right position at the shoulder, and holding a sleeping child more upright.
High-backed booster seats are available with or without Isofix attachments. Using Isofix brackets for a high-backed booster seat means that you don’t have to attach the car seat with the seatbelt even if you’re travelling in the car without your child. This is necessary because in the case of a collision, a loose car seat is a danger for the other passengers. Today it’s possible to find high-backed booster seats in all price classes. Some of these are simpler and some are more advanced, with functions such as a tilting seat unit, extra seatbelt protection or crotch straps for the seatbelt.