Britax KidFix i-Size Booster Seat

$399.00 Regular price $499.00
European-certified highback booster seat. Accommodates children from 3.5 to 12 years (100-150cm, 15-36kg). Offers ISOfix and 3-point seatbelt installation options.
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Designed, developed and manufactured in Germany, the Britax KidFix i-Size accommodates children from 15 to 36 kg (approx. 3.5 to 12 years). Thanks to its carefully placed air ventilation holes aid air circulation, the KidFix helps to keep your child comfortable for longer.

The Britax KidFix i-Size is designed with a slew of safety features to keep your mind at ease at the wheel. It's equipped with the proven technologies of XP-PAD and SecureGuard for frontal impact protection, whilst the new design SICT protects your child from side collisions. This clever guy is also fitted with SecureGuard, which helps position the lap belt over their pelvic bones to reduce the risk of injuries in their abdominal region.


Expert protection

The new KidFix i-Size has been designed and approved to the new i-Size standard, making it our safest KidFix* to date. Every feature on the seat has been developed with one thing in mind - maximum protection. The proven technologies of XP-PAD, SICT and SecureGuard, now combined with the redesigned seating area for optimum crash performance, offer all-round protection.

Comfort and practicality at its core

Comfort and practicality come as standard with the KidFix i-Size. The generously padded soft fabric covers and carefully placed air ventilation holes on the shell ensure your child travels in comfort for longer. The slim design of the seat allows for three KidFix i-Size seats to be installed in the back row of a wide range of cars, whilst the headrest markings help the parents find the right headrest height every single time.

Sustainable Quality – caring for the world our children grow up in

The cleverly engineered KidFix i-Size weighs around 1.3 kg lighter than its predecessor, and is designed and made in our factory in Germany – helping with shorter transport routes and minimising the impact on the environment. We’ve also replaced our packaging with sustainable options: you’ll find the KidFix i-Size packed in plant-based bags and recycled cartons from responsible sources. Even the mighty swift tags we use to attach product information are biodegradable on soil, resulting in no microplastics entering the ecosystem.

  • Forward facing installation: 100-150cm
  • Child weight: 15-36kg
  • Child age: approx. 3.5-12 years
  • Redesigned seating area for optimum crash performance
  • Unique protection for the neck and chest
  • Advanced Side Impact Protection – SICT
  • SecureGuard to protect abdominal area
  • Easy adjustable, ergonomic headrest for extra comfort
  • Air ventilation for comfort
  • Slim and compact design for three seats to be installed at the back easily
  • Removable cover for quick and easy cleaning
  • Highback booster protection


  • Booster weight: 6.7 kg
  • Booster dimensions: H 63 – 83 x W 48 x D 42 cm

Here is a short installation guide from the manufacturer for the Britax KidFix i-Size Booster Seat:


Belted with ISOfix Attachment Installation

This child car seat has to be installed using the vehicle’s 3-point seat belt as well as the ISOFIX anchorage points in your car. This ensures a firm and secure connection between the child car seat and car, even when your child is not sitting in it. KIDFIX i-SIZE features integrated ISOFIX connectors that enable you to attach the car seat to the ISOFIX anchorage points in your car. The ISOFIX installation system offers superior performance in the event of an accident when your child is secured with the car's 3-point seat belt and ensures that the car seat is always firmly attached to the car, even when it is not being used by your child. Check our vehicle list or FIT FINDER® on the product page to see if the car seat is compatible with your car.

Belted Installation

This child car seat can be installed with the car's 3-point seat belt. This option is handy if you will be transferring the car seat to different cars which may not all have ISOFIX anchorage points. Seat belt guides on the car seat will help you install the seat correctly. Check the vehicle owner's manual for suitable seating positions and ask your local retailer for a test installation in your car (please ask for a member of staff trained by Britax Römer), before you buy the car seat.

Download the Britax KidFix i-Size Booster Seat instruction manual.

The Britax KidFix i-Size Booster Seat is covered by a one-year warranty on manufacturing defects only. 

Keeping children safe is our utmost priority. As such, we have a strict no-return policy for child safety products as it is not possible to ascertain the complete history (how it was used/if any parts of the product might be compromised) of the product before considering resale.

We encourage you to contact us to ensure that this product is suitable for your family prior to purchase. 

For more information on our Returns Policy, visit our Returns Policy Page

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