Guide to buying a booster car seat


By the time your child reaches his fourth birthday, things will doubtless be getting a little snug in the strapping-into-car-seat department (unless you were farsighted/rich enough to buy a Group 1/2/3 car seat, in which case he or she won't feel snug for a long time yet).

But that doesn't mean you can chuck your child on to the back seat using nothing but the adult seat belt to restrain them.

It is a legal requirement that all children must travel in an 'appropriate' car seat until their 12th birthday, or until they are 1.35m tall, whichever comes first.

'Appropriate' in your older child's case usually means a booster seat (with or without a back support), which will lift him high enough to fit the adult seat belt safely - and give him a much better view out of the window. 

Safety | Weight categories | Portability | Installation | Comfort| Value for money | Car seats and the law


As with all car seats, remember to check that the booster seat you're going to buy has an E Mark, which shows that it conforms to all the officially required safety standards.

Most booster seats tend to fit securely into more makes of car than your average baby/toddler car seat. But it's still worth checking that your car is on the booster-seat-manufacturer's list of compatible car models before you buy. And even then, test the fit of the booster seat with your child in it before you part with any cash.

Check that the: 

  • Adult belt can be worn as tightly as possible
  • Lap belt goes over the pelvic region and not across the stomach
  • Diagonal strap goes over the shoulder and not the neck
  • Belt is flat and there are no twists

We don't ask Mumsnetters who review car seats to rate them for safety (as - thank goodness - most people don't get to test this particular feature first-hand), but we do encourage people to check the latest safety reports and contact the manufacturer direct if they have any specific safety concerns.

Weight categories

Car seats are categorised into groups by numbers and symbols, rather than by the weight of the child. So for a child weighing 15-36kg, and aged roughly four to 11 years, you're looking for a Group 2/3 seat. 

But if the car seat you bought your baby at about nine months is a Group 1/2/3 combination seat, you don't need to buy another one, and you're all set to travel safely for the next seven years. 

Talk with other parents


Most Group 2/3 seats are pretty lightweight and can be moved from car to car with ease, while the backless booster seats are often compact enough to be carried on a train or as hand luggage on a plane. They're also useful as spare seats. As one Mumsnetter says, "We always keep a booster in the boot in case we are giving my kids' friends a lift." 

While Group 1/2/3 combination seats can be used for longer, one of their drawbacks is that they can be trickier and heavier to move from car to car, making them less portable than the Group 2/3 seats. 


If you're having sweaty flashbacks to the first time you tried to fit an infant car seat in your vehicle, the good news is that booster seats are much easier to put in. Because they use the car's seatbelt, it's usually a matter of just strapping the child in as you would yourself - although most models have a 'belt guide' which the belt is threaded through and ensures a good fit. Some seats have strap slides, which secure the seatbelt further. 


For long journeys, seats with back and head rests are great for preventing heads from lolling about or falling forward as your child sleeps. Many models also have extendable headrests which 'grow' with the child, useful considering the difference in height between a four year old and an 11 year old. There are even models which offer padding, arm rests, side-wings and cup-holders (a big hit with most children).

Value for money

Group 2/3 seats vary in cost, depending on their size, shape and extras. It's obviously tempting to go for one of the cheapest models but, before you do, remember that this seat will last your child a long time, so it may be worth paying a bit more. And, of course, do remember that you should never buy any car seat second-hand, unless you know its complete history and are sure it's never been involved in an accident. 

Car seats and the law

According to car-seat regulations that came into force in 2006, it's the driver's responsibility to check that children travelling in the car are 'correctly restrained'. 

The law states that:

  • It is illegal for a child over three and under 12 (or 1.35m tall) to travel in the front or back of a car, unless the child is strapped into car seat that is suitable for her size.
  • The only exceptions to this rule are: travel by taxi or licensed hire car where there is no appropriate child restraint available (in which case, the child must wear the adult seat belt); a short, unexpected but important journey where there is no appropriate child restraint available (in which case, the child must wear the adult seat belt); the presence of two other occupied child car seats on the rear passenger seat that prevent fitment of a third seat (in which case, the child must wear the adult seat belt); and travel in a car with no adult seat belts fitted (in which case, the child should travel unrestrained in the rear).

The legal regulations are slightly different for children over the age of three (find them here) but all children must still travel in an appropriate car seat until either their 12th birthday, or they are 1.35m tall.