'i-size' is a new EU safety regulation for child car seats (ECE R129). It was introduced in July 2013 to make child car seats easier to fit, provide better protection from side impacts and keep children rearward-facing for longer. i-size only applies to Isofix seats.

What's the difference between Isofix and Isize?

The difference between i-Size and Isofix. i-Size/R129 currently requires the use of Isofix to fit your car seat, not seat belts. However, many i-Size car seats do still have the option of installing using the vehicle seat belt. Isofix is designed to make installing your car seat quick and easy.

What is Isize?

i-Size is a new European-wide car seat regulation (the first phase of a safety standard called R129), which aims to make car seats safer. Advertisement. It's designed to keep children rear-facing for longer, provide better side impact protection and make car seats easier to fit correctly.