The Best High-Back Booster Seats in the UK (2025): Compared

Choosing the right booster seat for your child is one of the most important safety decisions you'll make as a parent. With new models and evolving safety standards like R129 (i-Size), it can feel overwhelming to pick the right one. In this post, we compare four of the UK’s leading high-back booster seats — Axkid Nextkid, Avionaut MaxSpace AirFlow, BeSafe Flex FIX 2, and Joie i-Traver—to help you make an informed choice.

UK Booster Seat Laws at a Glance

In the UK, children must use an appropriate child car seat until they are either 12 years old or 135 cm tall, whichever comes first. Beyond that, they must wear an adult seatbelt. High-back booster seats are recommended for children from 100 cm to 150 cm tall, ensuring the seatbelt fits correctly across the child’s pelvis and shoulder.

Legal Requirements (As of July 2025):

Children must use a child car seat until they are either:

12 years old, or 135 cm tall (whichever comes first).

After this, they must use an adult seatbelt.

Types of Child Seats (By Age/Height):

Types of Booster Seats

1. High-Back Booster Seat (Preferred & Safer)

• Supports the child's head, neck, and torso.

• Guides the seatbelt into the correct position.

• Often has side-impact protection.

• Suitable for cars without headrests or for added safety.

2. Backless Booster Cushion

• Raises the child so that the seatbelt fits correctly over the shoulder and hips.

• Legal only for children over 22 kg and 125 cm in new purchases since 2017.

• Less protective in side impacts.

Key Safety Recommendations

• Use a high-back booster whenever possible, especially for younger or smaller children.

• Ensure the seatbelt sits across the pelvis and shoulder, not the stomach or neck.

• Only purchase seats marked with the ECE R44/04 or the newer R129 (i-Size) standards.

• Booster seats must be compatible with your car and fitted correctly.
  

🔧 Installation Methods:

• ISOFIX: Safer, easier to install, reduces installation errors.

• Seatbelt-fitted: More flexible but needs careful fitting.

• Some booster seats have belt guides or top tether attachments.
  
  

📑 Latest UK Recommendations:

• The R129 (i-Size) regulation, gradually replacing the older R44/04, recommends seats based on the child’s height, not weight.

• Side-impact testing is mandatory for all R129 booster seats.

• Booster cushions sold post-2017 must only be used by taller and older children.

Meet the Contenders

⭐ Axkid Nextkid

• Standard: R129 i-Size approved (100–150 cm)

• Safety: Known for robust side-impact protection and adjustable side wings.

• Comfort: Breathable ventilation channels, 4 recline options, and 8-position headrest.

• Installation: ISOFIX for quick and secure fitting.

• Key Benefit: Adjustable width accommodates growing children.

⭐ Avionaut MaxSpace AirFlow

• Standard: R129/03 approved.

• Safety: Excellent side-impact protection; certified by AGR for promoting healthy posture and spinal support.

• Comfort: Breathable mesh seat fabric and generous padding; ideal for longer journeys.

• Installation: ISOFIX compatible.

• Key Benefit: One of the roomiest and most ergonomic seats on the market, though slightly wider for small cars.

⭐ BeSafe Flex FIX 2

• Standard: R129 i-Size approved (100–150 cm).

• Safety: Advanced SIP+ side protection and energy-absorbing shell.

• Comfort: Adjustable recline and compact side wings.

• Installation: ISOFIX for secure attachment.

• Key Benefit: Combines slim design with adjustable comfort, ideal for fitting multiple car seats side by side.

⭐ Joie i-Traver

• Standard: R129 i-Size approved (100–150 cm).

• Safety: Includes side-impact panels and excellent seatbelt positioning guides.

• Comfort: Lightweight, with memory foam padding and 10 headrest positions.

• Installation: ISOFIX or seatbelt.

• Key Benefit: Great value, highly portable, and easy to move between vehicles.

Key Comparisons at a Glance

Comfort & Adjustability

• Nextkid: Machine-washable covers, 4-step recline, 8 headrest positions, and ventilation through shell

• MaxSpace AirFlow:

  • Breathable mesh keeps temperature regulated year-round.

  • Adjustable recline and deep lumbar support praised by users. 

  • Spacious width (~44 cm) – great for growth, may be bulky in small cars. 

• Flex FIX 2:

  • Reclining feature makes long trips more restful.

  • Side wings and PAD+ system improve comfort and safety 

• i‑Traver:

  • Weighs just 5.6 kg—easy to move between cars.

  • Offers padded armrests and memory‑foam cushioning; 10 headrest heights, 3 seat depths. 

🔄 Usability

• Installation

  • All models support ISOFIX; Joie and MaxSpace fit well in most cars.

• Bulk & Fit

  • MaxSpace is the widest and heaviest—great for comfort, less so for tighter spaces

  • i‑Traver is the most compact and lightweight while still comfortable 

• Maintenance

  • Nextkid and MaxSpace covers are removable and machine-washable.

  • MaxSpace’s mesh fabric is durable and resists heat and moisture 

📏 Longevity & Growth Accommodation

• Nextkid: Designed for children up to 150 cm (~12 years) with adjustable width and height. 

• MaxSpace: No weight limit, up to 150 cm; extends well even for tall kids. 

• Flex FIX 2: Follows standard 100–150 cm i‑Size range; good long-term option.

• i‑Traver: Height 100–150 cm, with adaptable seat depth and headrest for growth

Which Booster Seat Should You Choose?

• For growing room and ventilation: Axkid Nextkid

• For ergonomics and long-distance comfort: Avionaut MaxSpace AirFlow

• For top safety in tight spaces: BeSafe Flex FIX 2

• For portability and great value: Joie i-Traver

Final Thoughts

All four of these booster seats meet the latest UK and European safety standards and offer excellent protection for your child. The best choice comes down to your family’s specific needs: whether you prioritise long-trip comfort, ease of use across multiple vehicles, or fitting several seats in one car.

If you’d like help selecting the right model for your car type or child’s needs, feel free to reach out or check the latest deals at

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