Buying a booster seat: the Mumsnet guide

Ready to make the transition from a car seat to a booster? Here's everything you need to know in order to choose the right booster seat for your child

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Car seats and the law

Children in booster seats

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

It is a legal requirement that all children must travel in an 'appropriate' car seat until their 12th birthday, or until they are 135m tall (4ft 4in), whichever comes first. 'Appropriate' in the case of older children usually means a booster seat, which will lift them high enough to fit the adult seat belt safely - and give them a much better view out of the window. 

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 seats on the rear passenger seat, which prevent fitment of a third seat (in which case, the child must wear the adult seat belt)
  • travel in a car with no adult seat belts fitted (in which case, the child should travel unrestrained in the rear).

Bear in mind that new, stricter laws will be coming into force later in 2016, which will limit the use of backless booster seats. Under the new rules, backless booster seats will only be approved for use of children taller than 125cm (4ft 1in) and weighing more than 22kg (48.5lb).


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

Boosters 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 manufacturer's list of compatible models before you buy - and even then, test the fit of the seat with your child in it before you part with any cash. When doing so, you should check that

  • the adult belt can be worn as tightly as possible
  • the lap belt goes over the pelvic region and not across the stomach
  • the diagonal strap goes over the shoulder and not the neck
  • the 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 (33-79lb), 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. 


Child in car seat

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're 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 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, 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' through which the belt is threaded to ensure 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 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 that 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 secondhand, unless you know its complete history and are sure it's never been involved in an accident. 

Backless boosters vs high-back boosters

Don't be tempted to buy a backless booster over a high-backed booster just because it will save you a few quid. High-backed boosters are a much safer option for small children, as they hold a child more securely in place and offer protection in the event of a side-impact crash. 

Under new rules to be introduced later this year, high-back boosters will be compulsory for children shorter than 125cm (4ft 1in) and weighing less than 22kg (48.5lb).

More information on booster seats 

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Last updated: 6 months ago