Car Seat Stage Checker (UK)
Enter your child's height to see the correct car seat stage under current UK rules. Add their weight and age for a fuller picture. We'll never name or approve a specific seat – only the category.
Available 24/7 • Nothing stored on our servers • Height-based (R129 / i-Size)
Your child's measurements
Measure standing (or lying flat for babies), shoes off. Current UK seats are height-based, so this is the most reliable guide.
Used to cross-check the older weight-based groups.
Important for the rear-facing rule under 15 months.
The UK stages at a glance
Current UK seats are height-based (R129, also called i-Size). Older weight-based (ECE R44) seats are still legal to use if bought before the sales change – the groups are noted below for reference.
From birth, roughly up to around 87 cm. Always rear-facing. Weight-based equivalent: Group 0 / 0+ (up to 13 kg).
Roughly around 87–105 cm. Must stay rear-facing until over 15 months; extended rear-facing is recommended for as long as the seat allows. Weight-based equivalent: Group 1 (9–18 kg).
Roughly around 100–135 cm, using the adult seat belt. A backless booster cushion is only suitable once a child is over 125 cm and 22 kg. Weight-based equivalent: Group 2/3 (15–36 kg).
Children normally need a car seat until they're 12 years old or 135 cm tall, whichever comes first. After that, an adult seat belt.
Based on current UK rules published on GOV.UK. For choosing and fitting a seat, see childcarseats.org.uk.
General guidance only. This tool reflects current UK rules but is not a substitute for the manufacturer's instructions or a professional fitting check. Your seat's manual and your car's compatibility always take priority – and the fit should be checked in person.