Car Seat

When to upgrade your car seat

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Not sure when’s the right time to move up a car seat? Read on for expert advice from Pit Stop specialist Adam from our Lakeside store.

Is it time for a new car seat?

It’s amazing how quickly they grow up. All of a sudden your newborn baby bundle is nearly nine months old and on the move! But how do you know when it’s time for a new car seat?

Remember: think height & weight.

There’s no denying it: little ones grow at different rates – so using age alone to determine which car seat is needed can be risky. That’s why we now use height or weight as the deciding factors.

Which car seat will I need?

Car seats are categorised into groups, so we’ve taken a look at each one and created a handy checklist for you to determine when an upgrade’s required.

Group 0+ 

Otherwise known as infant carriers, these rear-facing seats are ideal for the early months. But how long should your little one use this seat for?

You shouldn’t upgrade a Group 0+ seat until:

• Your child is at least 9kg; and
• They can sit upright, unaided, for 20-30 minutes a day – over a 6-8 week period.
• The crown of your child’s head is level with the top of the seat’s shell; and
• The harness is more than 2cm below your child’s shoulder.

group 0+ car seat

Group 0+ infant carrier

Group 0+/1

Otherwise known as a combination seat, these provide the best of both worlds: allowing baby to sit in the safest rear-facing position for the early days, then switching to a forward-facing position once they get a little bigger. There are a few things to remember here:

• Always keep baby rear-facing to 13kg. Some newer models, however, (like the Britax Dualfix) let your child travel in the recommended rear-facing position to 18kg.
• Only upgrade from this seat once little one weighs over 18kg.

group 0+1 car seat

Group 0+/1 combination car seat

Group 1

Providing the ideal follow-on to a Group 0+ infant carrier, these shell-shaped, forward-facing seats provide optimised protection. With most having multi-recline positions, they’re a sleepy toddler’s best friend. You should only upgrade from a Group 1 seat when:

• Your child weighs between 15 – 18kg
• Their eyes are level with the top of the seat shell
• The harness is below the shoulder level

group 1 car seat

Group 1 forward facing car seat

Group 1/2

This multi-stage seat has the option of travelling in the recommended rear-facing position for longer. Suitable from approximately 9 months to 6 years, they’re a great long term investment. Depending on model, you will need to upgrade this seat when:

• Your child weighs between 18 – 25kg.

group 1/2 car seat

Group 1/2 combination/rear facing car seat

Group 1/2/3

Designed for when little one has outgrown their carrier, this multi-group seat can be used for the rest of their car seat days. With this group, there are just a few pointers to bear in mind:

  • Make sure your child’s head is positioned in the middle of the seat’s headrest
  • The built-in harness must be used while your child weighs between 9 – 18kg
  • Once they weigh 15kg, you can remove the built-in harness and use the car’s seatbelt

You can only start using an adult seatbelt when your child is:

  • 12 years old; and
  • 135cm tall
group 2_3 car seat

Group 1/2/3 highback boosters with harness

Group 2/3

The final stage in the car seat journey! This highback booster can be used once your child weighs 15kg, and is suitable up to 36kg. Some models have a detachable backrest too, leaving just the bottom booster cushion for support. As with Group 1/2/3, only start using an adult seatbelt when your child is:

• 12 years old; and
• Over 135cm tall.

Although it’s suitable up to 36kg, if your child’s weight exceeds this, but they haven’t met the above criteria, we’d still recommend using it – it’s safer than not using anything!

group 1_2_3 car seat

Group 2/3 highback booster

The general rule of thumb is to choose a car seat that’s rear facing for as long as possible – moving to a forward facing position too soon can be dangerous because baby’s neck may not be sufficiently developed to support a relatively heavy head. Keeping rear-facing for longer is always safest.

Whichever takes your fancy, make sure it’s checked by a specialist as not all seats will fit in all cars.

Kiddicare car seat fitting

What about upgrading i-Size car seats?

i-Size is the new European legislation designed to improve the safety levels of car seats. They are all are ISOFIX seats and all go through rigorous testing, including – for the first time ever – side impact testing. Rather than relying purely on weight, i-Size uses height AND age for its classification. With an i-Size seat, remember:

• Only switch to a forward-facing position once baby is 75-80cm and 15 months old.

Any other questions about i-Size? Have a look at our handy video – i-Size explained – or pop into any Kiddicare store and a member of the Pit Stop crew will happily give you a demo.

Adam answers your FAQs about car seat upgrades

Q. “My baby has just turned 9 months, do I need to upgrade their Group 0+ car seat?”

A. “Not necessarily: Car seat suitability is measured by height and weight – depending on your baby, they could still get a few more months out of their seat!”

Q. “Can I use a second-hand car seat?”

A. “Legally you can, but we’d always recommend buying a new seat: the second-hand seat may have been involved in an accident, or have been dropped; you can never be sure how it’s been stored; and it may have parts missing.”

Q. “Does a car seat have a life span?”

A. “Yes, it does. On average it’s 10 years from date of manufacture (which can be found on the orange sticker), but this varies from model to model.”

Q. “Can I use 3 car seats in the back of my car?”

A. “Yes, but only when there is a full sized seat in the middle and a gap between each seat – this will prevent a transfer of force through the seats on impact.”


Still unsure which seat is right for your little one? To help, we’ve created a handy guide on choosing the perfect car seat. Or pop into your local Kiddicare and one of our Pit Stop crew will be happy to advise. Already got a car seat? We’ll make sure it’s safely fitted while you’re there, no matter where or when you bought it.