Which car seat does my child need?
Children move through four stages: a rear-facing car seat, a forward-facing seat with a harness, a booster seat and finally the seat belt. This car seat calculator tells you which stage fits your child now, using their age, whether they have outgrown their current seat’s limits, and whether the adult seat belt fits them properly — following the US National Highway Traffic Safety Administration (NHTSA) recommendations.
It also shows the legal rules where you drive: the UK’s “12 years or 135 cm” rule and its seat groups, India’s child-restraint and two-wheeler rules, and a reminder that each US state has its own law. It is information only; your seat’s labels and manual come first.
How to use the Car Seat Stage Finder
- Choose where you drive and enter your child’s age; add weight and height if you know them.
- Tick whether your child has reached the top limits of the rear-facing mode or the forward-facing harness of their seat — the limits are printed on the seat’s label.
- For children over 8, sit them in the car without a booster and tick the two belt-fit checks if the belt sits correctly.
- Read the recommended stage, why, and the rules for your country.
Car Seat Stage Finder features
Four stages
Rear-facing, forward-facing with harness, booster and seat belt, shown as a ladder.
NHTSA guidance
The age bands and the rule to move up only when a seat’s limits are reached.
UK law
Child seat until 12 or 135 cm, i-Size rear-facing to over 15 months, and the R44 weight groups.
India rules
Child restraint for under-14s in cars and the harness-and-helmet rule for 9 months to 4 years on motorcycles.
Seat-belt fit check
The two checks NHTSA uses to decide when a booster is no longer needed.
Car seat stages by age (NHTSA)
| Age | Recommendation |
|---|---|
| Birth – 12 months | Always rear-facing (infant-only, convertible or all-in-one seat). |
| 1 – 3 years | Rear-facing as long as possible, until the seat’s top height or weight limit; then forward-facing with harness and tether. |
| 4 – 7 years | Forward-facing with harness until its top limit; then a booster seat in the back seat. |
| 8 – 12 years | Booster until the seat belt fits properly; always in the back seat. |
UK child car seat law
- Children must normally use a child car seat until they are 12 years old or 135 cm tall, whichever comes first.
- Height-based (i-Size, R129) seats must face the rear until your child is over 15 months.
- Weight-based (ECE R44) seats come in groups: 0 (0–10 kg), 0+ (0–13 kg), 1 (9–18 kg), 2 (15–25 kg) and 3 (22–36 kg). New booster cushions are only made as group 3.
- Switch off the front airbag before fitting a rear-facing seat in a front seat, and never fit a child seat in a side-facing seat.
India: child seats and two-wheelers
Since 1 September 2019, section 194B(2) of the Motor Vehicles Act makes it an offence to drive with a child under 14 who is not secured by a safety belt or a child restraint system (fine ₹1,000). Since February 2023, rule 138(7) of the Central Motor Vehicles Rules requires a child aged 9 months to 4 years riding pillion on a motorcycle to wear a crash helmet and be attached to the rider with a safety harness, with speed limited to 40 km/h. The law does not set seat stages, so the stage shown follows NHTSA. For new-baby shopping, see the newborn essentials checklist.
Car Seat Stage Finder FAQ
When can my child face forward in a car seat?
NHTSA advises keeping children rear-facing as long as possible, until they reach the top height or weight limit of their seat’s rear-facing mode. In the UK, height-based seats must face the rear until a child is over 15 months.
What are the booster seat requirements for height and weight?
NHTSA uses fit rather than numbers: keep a booster until the lap belt lies across the upper thighs and the shoulder belt across the shoulder and chest. In the UK, a child seat is required until 12 years or 135 cm, and group 3 boosters cover 22–36 kg.
Which car seat is right for a baby from 0 to 4 years?
Start rear-facing; a convertible or all-in-one seat can stay rear-facing longer than an infant seat. Move to a forward-facing harness only when the rear-facing limits are reached.
Can my child sit in the front seat?
NHTSA advises the back seat at least through age 12. In the UK, a rear-facing seat may only go in the front with the airbag switched off.
Does this cover my US state’s law?
No. It follows federal NHTSA guidance; state laws differ, so check your state’s rules too.