The 5 best high-back booster seats for 2026
Compare five high-back boosters for the 100–150 cm stage, from a light budget seat to folding and ISOFIX options, with the fit checks that matter.
A high-back booster uses the car’s three-point seat belt to restrain your child, with the seat guiding that belt across their shoulder and pelvis. Our five picks cover the 100–150 cm stage, but they differ noticeably in weight, storage and headrest design. The right choice also needs to fit your child and the seating position in your car.
Feature | |||||
|---|---|---|---|---|---|
| Best for | Best for Lightweight value | Tilting headrest | Folding and storage | Budget ISOFIX | Open buckle access |
| Height range | Height range 100–150 cm | 100–150 cm | 100–150 cm | 100–150 cm | 100–150 cm |
| ISOFIX anchors | ISOFIX anchors No | Optional | Optional | Optional | Optional |
| Seat weight | Seat weight 3.4 kg | 7 kg | 5.32 kg | 6.4 kg | 5.7 kg |
Before moving to a high-back booster
Reaching 100 cm is not, by itself, a reason to switch. Your child also needs to sit upright and keep the belt correctly positioned throughout the journey, including when asleep. This stage is usually around age four onwards. Keep using a suitable harnessed seat, including rear-facing where its limits permit, until it is outgrown rather than moving early for convenience.
All five seats need a three-point lap-and-diagonal belt. ISOFIX anchors secure the booster to the vehicle; they do not replace the belt around your child.
The five high-back boosters to compare
1. Graco Junior Maxi i-Size high-back booster seat
The Graco Junior Maxi i-Size is our first pick for a simple, inexpensive booster that moves between cars. At 3.4 kg, it is the lightest seat here. Its seat-belt-only fitting also makes sense for a grandparent’s car without ISOFIX, provided the vehicle and belt fit are suitable.
Why did we choose this product?
Ten headrest positions let you raise the shoulder-belt guide as your child grows, while the two retractable cupholders are a useful everyday extra. The removable cover can be washed at 30°C. It offers the basics without the extra weight of ISOFIX connectors or a folding mechanism.
Keep in mind
There is no ISOFIX attachment, so buckle the empty booster in as the manual instructs. Route the belt through the specified guides and under the armrests; check that it retracts freely after your child leans forward. The backrest must stay attached. Try the seat at its taller settings too, because vehicle fit can become restricted above 135 cm.
Features that may help you
•Best for: low cost and frequent car swaps
•Approved height: 100–150 cm
•Child restraint: three-point vehicle seat belt
•ISOFIX: no
•Seat weight: 3.4 kg
2. CBX by CYBEX Solution X i-Fix high-back booster seat
The CBX Solution X i-Fix is worth shortlisting for longer journeys with a child who tends to nod off. Its headrest has three tilt positions, as well as 11 height settings. That gives it a useful comfort adjustment missing from the more basic Graco.
Why did we choose this product?
The tilting headrest is designed to help keep the child’s head within the side supports. The backrest adjusts to the vehicle seat, and ISOFIX connectors hold the booster in place where the car permits them. Belt-only fitting is also allowed. A removable, washable cover makes it practical for everyday use.
Keep in mind
At 7 kg, it is the heaviest choice here, so it makes more sense left in one car than carried between vehicles. A tilting headrest cannot keep a slumping child correctly positioned by itself: the shoulder belt must still stay on the shoulder. Check clearance at full headrest height, particularly above 135 cm. Choose the R129 Solution X i-Fix named here, rather than assuming an older Solution X-Fix has the same approval.
Features that may help you
•Best for: headrest adjustment on longer journeys
•Approved height: 100–150 cm
•Child restraint: three-point vehicle seat belt
•ISOFIX: optional, subject to vehicle compatibility
•Seat weight: 7 kg
3. Maxi-Cosi Tanza i-Size high-back booster seat
The Maxi-Cosi Tanza i-Size is the most useful option here if the booster regularly needs to fit in a cupboard or car boot. It folds to roughly 45 × 60 × 26 cm, so it is easier to store between visits or lifts than a full-height booster.
Why did we choose this product?
At about 5.3 kg, it is lighter than the Kinderkraft and CBX, though not as light as the Graco. Ten headrest positions, padded upholstery and a 30°C-washable cover provide the everyday essentials. ISOFIX is recommended where available; its manual also permits fitting with the three-point seat belt alone.
Keep in mind
The fold is useful between journeys, not a substitute for checking the seat once it is unfolded and fitted. If it will stay in one car, you may get more use from the CBX’s headrest adjustment than from Tanza’s storage feature. Try your child in the seat and check access to the vehicle buckle before buying.
Features that may help you
•Best for: folding and storage
•Approved height: 100–150 cm
•Manufacturer’s child-weight guide: 15–36 kg
•Child restraint: three-point vehicle seat belt
•ISOFIX: optional; recommended where available
•Seat weight: 5.32 kg
4. Kinderkraft JUNIORFIX2 i-Size high-back booster seat
The Kinderkraft JUNIORFIX2 is a lower-cost route to ISOFIX if the Graco’s lack of connectors is the main reason you would rule it out. The padded seat, ten-position headrest and removable cover make it a straightforward option for regular school runs.
Why did we choose this product?
Its connectors have indicators to help you check engagement, while belt-only use is permitted in suitable vehicles. ADAC rated the exact Junior Fix 2 i-Size good overall in May 2026, but its safety assessment was only satisfactory, with average results in both frontal and side impacts. That makes the value and fit the reasons to consider it, rather than a claim of leading crash performance.
Keep in mind
The manufacturer lists 6.4 kg, so it is a substantial step up from the Graco if you carry the seat frequently. During a trial fitting, check that the shoulder belt slides back through its guide and that the armrests leave room to reach the buckle. The black and grey versions linked here are JUNIORFIX2; the similarly named PRO is a separate variant.
Features that may help you
•Best for: ISOFIX on a smaller budget
•Approved height: 100–150 cm
•Child restraint: three-point vehicle seat belt
•ISOFIX: optional, subject to vehicle compatibility
•Seat weight: 6.4 kg
5. Maxi-Cosi RodiFix R i-Size high-back booster seat
The Maxi-Cosi RodiFix R i-Size is the choice to try if bulky armrests make buckling awkward. Its open-sided seat area has low belt guides, and the Authentic Graphite version has breathable ClimaFlow fabrics. It is a practical step up for a booster that stays in the family car.
Why did we choose this product?
The ten-position headrest and 5.7 kg build sit between the lightweight Graco and heavier CBX. In ADAC’s October 2024 test, the exact RodiFix R scored 2.0 overall (good), with 2.5 for safety and 1.5 for handling. Its frontal-impact result was average and side-impact result good; the overall score should not be read as a crash-only rating.
Keep in mind
This recommendation is for the RodiFix R, not the M, S or Pro. It does not fold like the Tanza, and the open buckle area cannot compensate for a buckle trapped beside another seat. The manual permits belt-only installation, while recommending ISOFIX where available. An adult should still check the belt after a child buckles themselves in.
Features that may help you
•Best for: open buckle access and breathable upholstery
•Approved height: 100–150 cm
•Manufacturer’s child-weight guide: 15–36 kg
•Child restraint: three-point vehicle seat belt
•ISOFIX: optional; recommended where available
•Seat weight: 5.7 kg
Check the child and car before buying
Try the seat in the car with your child if possible. If buying online, check the manufacturer’s compatibility guidance and the retailer’s returns terms first. A quoted width cannot tell you whether the buckle will remain accessible beside a sibling’s seat.
- Check the exact model’s height range, any stated weight limit and approval label. Age ranges are only a guide.
- Confirm the intended seating position in both the booster and vehicle manuals. Check ISOFIX compatibility if you plan to use it.
- Raise the headrest for your child and check that the vehicle headrest or roof does not obstruct it. Some boosters have more restricted vehicle compatibility above 135 cm.
- Route the belt through the specified guides. The lap section should lie low across the pelvis, and the diagonal section across the shoulder and chest.
- Ask your child to lean forward and sit back: the belt should retract without catching in the guide. Check that the vehicle buckle is accessible and does not press against the booster’s frame or belt guide.
For the distinction between approval labels, independent tests and a proper fitting, read our car seat safety and fit guide.
What do R129, i-Size and Group 2/3 mean here?
These five are height-based R129 boosters for 100–150 cm. You may also see “Group 2/3” in shop listings, but that is older weight-based R44 terminology. Use the exact seat’s label and instructions, rather than treating a familiar group name as proof of suitability.
UK law normally requires a child car seat until age 12 or 135 cm tall, whichever comes first. That legal threshold is separate from whether the adult belt fits well. A child may still benefit from an appropriate booster beyond 135 cm, within the booster’s limits.
Keep the belt fitting properly every journey
Before setting off, check the headrest height, remove belt twists and pull out slack. The lap belt needs to stay low, with the diagonal belt on the shoulder. Never put it under an arm or behind the back. Follow the model’s marked route, including its armrest or lower-guide instructions.
Watch for slumping when your child falls asleep. A reclining headrest may help support the head, but it does not make poor belt position acceptable. Stop safely to correct the position if needed. Avoid adding unapproved cushions, straps or accessories to hold a child in place.
Keep the backrest attached and secure the empty booster as its manual directs. If using ISOFIX, check both connectors have engaged; for belt-only use, buckle the empty seat in. Recheck fit when your child grows or the seat moves to another car.
FAQ
References:
- GOV.UK: child car seat rules
- RoSPA: high-back booster seats and belt fit
- RoSPA: using child car seats
- Graco: Junior Maxi i-Size R129 specifications and instructions
- CBX by CYBEX: Solution X i-Fix user guide
- Maxi-Cosi: Tanza i-Size features and specifications
- Kinderkraft: JUNIORFIX2 i-Size and instructions
- ADAC: Junior Fix 2 i-Size, May 2026 test
- Maxi-Cosi: RodiFix R i-Size features and specifications
- Maxi-Cosi: RodiFix M/R i-Size user guide
- ADAC: RodiFix R, October 2024 test
