Group 2/3 seats or high-backed boosters are the final stage car seats, for 'big kids’. They'll last until your child is 135cm tall/ 36kg (around 12 years old), and they no longer need a car seat anymore.


There are, of course, safety aspects when using car seats, and we've answered all the questions below, just scroll down. Or you can click here to go directly to the list of the best Group 2/3 car seats with a 5-point harness.

When should I change to a Group 2/3 car seat?

When a child weighs more than 15kg, which is roughly around 3-4 years, they can sit forward-facing and use a Group 2/3 car seat.

Most Group 2/3 car seats secure children with the car’s 3-point seat belt, and not a 5-point harness or impact shield they'll be used to from a Group 0+ and Group 1 seat.

Although children over 15kg will be safe using a car seat belt, as a parent of a larger or heavier child who needs to move onto the next stage, you may still want them restrained with a harness.

More like this

The solution is a Group 2/3 car seat that allows you to use a harness or impact shield well past the 15kg norm and we’ve found the best.

Do Group 2/3 car seats come with ISOFIX?

Group 2/3 seats can be installed in a variety of ways, many are now being made with ISOFIX system, which allows you to anchor the seat directly to the frame of your vehicle.

It makes it easy to install your car seat correctly and simply, as you just click in. However, it’s worth noting not all cars have ISOFIX, and you will have to check if the seat is compatible with your car.

Can I use seat belts to fit a Group 2/3 car seat?

Yes, there are still seat belted chairs, they are called Universal fit seats, and they can be fitted in most cars. It is worth noting that these kind of chairs are gradually being replaced by ISOFIX chairs.

What age can I use a backless booster cushion?

The law on backless boosters (booster cushions) changed in March 2017, children have to be:

  • Taller than 125cm tall (4ft1)
  • Weigh more than 22kg (3 stone 6.5 pounds) to sit on backless booster cushions

You can find all the information on booster seats and backless cushions in our safety article here.

How much will a harnessed Group 2/3 car seat cost?

Unlike the high-backed booster seats without harnesses these seats aren’t the cheapest, they range from £175 to £295.

We know price is important, but it’s worth remembering it’s not an gauge of the safety or security of a seat, especially as all car seats are tested to set safety standards.

It’s more important to choose the right seat that works best for you, your car and your child. Remember, don’t settle for second best – or secondhand car seats.

See the best Group 2/3 car seats with a 5-point harness on the market


1. Diono Radian 5 (Group 0+/1/2), £295

  • Harness to: 25kg (rear and forward-facing)
  • Age suitability: Birth - 25kg (Newborn - 6 years)
  • Rear-facing until: 25kg (around 6 years)

The Diono Radian 5 won our bronze medal for best rear-facing for longer car seat because it allows children to sit rearward facing from birth until 25kg (approx 5-6 years old).

The 5-point harness on this seat goes up to a massive 25kg, which is brilliant for larger or heavier toddlers and kids.

The Radian also folds for storage or transporting, and comes with added extras like a cup holder.

Our reviewer calls the Radian 5 “a sturdy and comfortable seat with some well thought out safety features like a steel frame, reinforced sides and super grip harness pads to reduce the impact of crash forces, while the lifetime warranty offers peace of mind.”

Read the full Diono Radian 5 review here.

You can buy the Diono Radian V from Uber Kids


2. Britax Multi-Tech II (Group 1/2), £260

  • Harness to: 18kg forward-facing or 25kg rear-facing
  • Age suitability: 9 months - 25kg (9 months - 6 years)
  • Rear-facing until: 25kg

A ground-breaking car seat when first released in 2009, the Multi-Tech 11 allows children to sit rear-facing to 6-years-old, and a harness that can be used up to 18 kg or 25kg depending on which position your child is facing.

This seat is ideal for people with older cars that don’t have ISOFIX connectors, as the Mutli-tech 11 can be fitted with the car seat belt. It also has a foot prop and lower tethers to provide extra stability when installed.

Read the full review of the Britax Multi-Tech II car seat

The Britax Multi-Tech II is available to buy at Pram Centre


3. Graco Nautilus Elite (Group 1/2/3), £149.99

  • Harness to: 18kg forward-facing
  • Age suitability: 9 months - 36kg (9 months - 12 years)
  • Forward-facing only

A Group 1/2/3 car seat, the Nautilus Elite is a forward-facing only car seat, and has a no-rethread 5-point harness to 4 years.

The Nautilus Elite comes with a cup holder, arm rests and toy storage, that the kids will no doubt love. It’s also one of the cheaper car seat options, as it’s a car seat that lasts 12 years and only costs £149.99.

See the complete review of the Nautilus Elite here.

You can buy the Graco Nautilus Elite car seat from Argos


4. Joie Bold (Group 1/2/3), £175

  • Harness to: 25kg forward-facing
  • Age suitability: 9 months - 36kg (9 months - 12 years)
  • Forward-facing only

This forward-facing car seat from Joie has a no-rethread, 5-point harness up to 25kg, but you can use it as a belted booster seat from 15kg, if you want to.

The Bold features 3 recline positions, side impact protection and removable cup holder for the kids. Installation-wise it is fitted in the car with ISOFIX, so there’s less room for installation error.

We've got the full, in-depth review of the Joie Bold here

You can buy the Joie Bold car seat from Online4Baby.


5. Multimac 3 or 4-seater car seat (Group 0+/1/2/3), from £1250

  • Harness to: 36kg forward-facing
  • Age suitability: Birth - 36kg (Newborn - 12 years)
  • Rear-facing until: 15 months

The Multimac is a one of a kind of car seat, it’s made to fit 3 or 4 children in the back of most medium-sized cars. Suitable from birth to 12 years, it has a variety of seating combinations, one of which includes rear-facing to 15 months.

But it’s the fact that it uses a 5-point harness all the way up to 36kg, which is 12 years, years longer than any other child car seat.

Our MFM mum-of-4 reviewer calls the Multimac a “space saving, super safe alternative to multiple car seats and allows so much flexibility”.

Read the full review of the Multimac car seat here

You can buy this seat from the Multimac website


6. Cozy N Safe Excalibur (Group 1/2/3), £249

  • Harness to: 25kg forward-facing
  • Age suitability: 9 months - 36kg (9 months - 12 years)
  • Forward-facing only

An ideal car seat if you plan on using it in multiple cars, as the Cozy N Safe Excalibur can be installed in a car both with ISOFIX and the car seat belt.

Suitable for children from 9 months to around 12 years, the Excalibur harness can be used up to 6 years.

Called an “impressive seat” by our MFM reviewer, our mum-of-2 says the Excalibur has a “slimline design that provides plenty of protection whilst still being a comfortable and stylish addition to our car”.

Read the full Cozy N Safe Excalibur review

You can buy the Cozy N Safe Excalibur from Kiddies Kingdom.


7. Kiddy Guardianfix 3 (Group 1/2/3), £279

  • Harness to: impact shield to 18kg
  • Age suitability: 9 months - 36kg (9 months - 12 years)
  • Forward-facing only

Unlike the other seats in this list the KiddyGuardianfix 3 uses an impact shield and not a 3-point harness. An alternative to straps or belts, impact shields are a bit Marmite in the UK.

They're the cause of a heated debate, with some brands championing shields and others hating them.

Love or hate the shields, they are certified as safe as harnesses and this seat in particular is easy-to-fit and uses ISOFIX or the car’s seat belt. What’s more the Kiddy Guardianfix has been approved for use in aircraft when in Group 1 mode!

Available from: Kiddies Kingdom


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Hazelann WilliamsFormer Reviews Editor

Having been a journalist for 15 years – and Reviews Editor at MadeForMums for five of those – Hazelann has accrued a lot of experience testing and reviewing every baby product imaginable.