R44/04 is an older European car seat standard that has been in use since 1995. This standard defines the safety requirements and testing methods for car seats. Car seats compliant with the R44/04 standard have been tested in front and rear crash tests and are categorized based on the child's weight into the following groups:

• Group 0+: from newborn up to 13 kg
• Group 1: 9-18 kg
• Group 2/3: 15-36 kg (up to approximately 12 years old)

Although car seats compliant with the R44/04 standard can still be used, the newer R129 standard has replaced it for new car seats. The R129 standard includes stricter testing requirements, including side-impact tests, and is based on the child's height and age rather than weight.