The legal basics in the UK
Children must normally use a suitable child car seat until they are 135cm tall or 12 years old, whichever comes first. After that, an adult seat belt is required.
Seats sold in the UK are approved to one of two standards. R129, also called i-Size, selects the seat by your child's height and requires rear-facing travel until at least 15 months. The older R44 standard selects by weight. Both can be legal to use, but i-Size is the current standard and what you'll find on sale new.
- Rear-facing until at least 15 months in an i-Size seat, and longer is safer.
- A rear-facing seat must never be used in a front seat with an active airbag.
- Backless booster cushions are only approved for children over 125cm and 22kg.
Fit is the part people get wrong
A correctly chosen seat fitted badly protects a child less well than a cheaper seat fitted properly. Fit is the highest-value thing you can get right, and it costs nothing.
Check whether your car has ISOFIX anchor points. If it does, an ISOFIX seat removes most of the ways a belt-fitted seat can go wrong. If it doesn't, you need a seat designed for belt fitting, and you should read the routing instructions carefully.
Not every seat fits every car, even with ISOFIX. Manufacturers publish vehicle fitting lists. Check yours before you commit to a model — many retailers and services will also fit-check for you in person.
Decide the exact model that fits your car and your child. Then, and only then, go and find the best price for it.
Never buy a car seat second-hand
This is the one baby item where the used market should be off-limits. A seat that has been in a collision can be structurally compromised in ways that are invisible, and you cannot verify the history of a seat from a stranger.
The same applies to a seat you've owned that has been in a crash: it should be replaced, even if it looks fine. Check for a manufacture date on the shell too — plastics degrade, and manufacturers give a usable lifespan.
What extra money buys — and doesn't
Every seat legally sold in the UK meets its approval standard. Paying more buys easier installation, better recline and rotation, more generous side protection, longer usable height ranges and better fabrics.
Rotating seats are a genuine daily convenience if you're lifting a baby in and out several times a day. Extended rear-facing seats keep a child rear-facing for longer, which is safer. Those are reasonable things to pay for. A higher price on its own is not evidence of a safer seat.
Timing and price
Car seats follow ordinary retail patterns — they can be discounted in sale periods and when models are refreshed. There's no rule that says a particular month is cheapest, and it's not worth delaying a seat you need in order to chase one.
What is worth doing is checking the same model across several retailers once you've decided. Prices on identical car seats vary meaningfully, and unlike formula there's no restriction on discounting them.
- Confirm the exact model name and variant — trims differ.
- Check whether the base is included or sold separately; this is a common price difference.
- Include delivery in the comparison.