The R129 (i-Size) Standard
At Axkid, safety begins with understanding the standards that protect your child. The UN Regulation No. 129 (R129), commonly known as i-Size, is the European safety approval for child car seats. It ensures advanced crash protection, mandatory side-impact testing, and height-based seat selection for a safer, simpler, and more accurate fit. From September 2024, all new car seats sold in the EU must comply with R129, replacing the older R44 regulation.
What is R129?
R129 is the European safety regulation that defines how child car seats are designed, tested, and approved. Unlike the previous R44 standard, which classified seats by weight, R129 uses child height as the main factor. This makes it easier for parents to select the right seat and reduces the risk of misuse.
For ISOFIX-installed seats, a maximum combined weight of 33 kg (child + seat) applies to ensure the anchoring system performs correctly. For belt-installed seats, only the child’s height is specified, although manufacturers may add weight or age guidance voluntarily.
All R129-approved seats must also pass side-impact testing, offering a higher level of protection than R44-approved seats.
What is i-Size?
i-Size is a defined part of the R129 regulation that ensures universal compatibility between child car seats and vehicles. An i-Size seat must be installed using ISOFIX connectors, and i-Size-approved cars include dedicated seating positions designed for a perfect fit.
In simple terms: all i-Size seats meet R129 requirements, but not all R129 seats are i-Size. This system makes car seat installation easier, more consistent, and significantly safer by reducing the risk of incorrect fitting.
Key improvements with R129
R129 represents a major leap forward in child car seat safety, built on modern crash research and real-world data. Its most significant advancements include:
- Height-based classification for simpler seat selection.
- Enhanced side-impact testing for improved lateral protection.
- Advanced Q-series crash test dummies providing more accurate injury data.
- Rear-facing travel requirement up to at least 15 months of age.
From September 2024, R129 will fully replace R44 for all new car seats sold in the EU, ensuring that every product meets the most advanced safety standards ever introduced in Europe.
Why R129 matters for parents
R129 was created to make choosing and using a car seat simpler and safer. By focusing on height, side-impact performance, and secure ISOFIX installation, this regulation gives families extra confidence that their seat fits correctly and provides protection in all directions.
At Axkid, we take our testing even further. Once a seat is R129 approved, we keep testing. We push it with higher speeds, stronger forces and larger test dummies than the regulation requires. We run it through Axkid Overtesting, challenge it in the Swedish Plus Test, and let independent bodies like ADAC test it too, to make sure it’s safe not just in a test lab, but in real life.
R129 proves a seat is legal. We prove it’s ready for real life.