Car seat dilemma - is it time to change?

It’s common to think that the age of your child is the best way to work out which car seat they should travel in but it’s actually a question of whether they are tall enough. 

Written by Elvira Lazar - Manager, Safety and Education
March 2019

We have laws on child restraints that refer to the age of children and also best practice guidelines that refer to the size of children. No wonder some parents are left wondering why there is a difference and what the best thing is to do!

The law outlines an age range as a guide. However, it's important to work out what type of restraint is suitable for children depending on their height, not their age. Just because a child meets the minimum age requirements, doesn't mean they are ready to upgrade thier seat. 

Age is not a good predictor of what the best type of restraint is. 

When is the right time to change your child's car seat?

To put it simply, the right time to change to a new child car seat is when a child outgrows the one they’re currently using. If they’ve met the minimum age requirements for the next seat but still fit in their existing seat then it’s safest to keep using their current one until they outgrow it, regardless of their age. There is danger in moving a child into the next seat too early because it is less likely to protect them properly in a crash if it doesn’t fit them properly.

the right time to change to a new child car seat is when a child outgrows the one they’re currently using

How can I tell if my child is tall enough?

Shoulder height markers help you make this call. You can check if your child still fits in thier seat by checking if their shoulders still fit between the shoulder height markers labelled on the restraint. 

Rearward facing child restraint diagram


Moving from a rearward facing car seat to forward facing

To work out when it’s time to change rearward facing child car seats to forward facing, check if your child’s shoulders pass the highest slot on the seat.

check if your child's shoulders pass the highest slot on the car seat

When my son was 6 months old, he wasn’t particularly small. He was actually Mr. Average in terms of height. But he wasn’t tall enough to fit into a forward facing seat until he was 8 months old. If I had turned him around at 6 months of age, he wouldn’t have been travelling a safely as possible.

Now, things can get a little tricky because all seats are different. Some rear facing car seats will accommodate taller babies. The same baby will outgrow another restraint earlier. The key here is to keep them is the seat they’re using until they no longer fit. Try to look for restraints with taller backs when you’re shopping for a seat.

Forward facing child restraint diagram


Moving from a forward facing car seat to a booster

It’s safe to move children into a booster seat when their shoulders no longer fit within the range of the shoulder height markers of their forward facing restraint. At age 4 years, my son still fit into his forward facing seat and wasn’t ready for a booster until he was five and a half.

don’t transition kids if their shoulders are within the range of the shoulder height markers

The height on the back of a forward facing seat can also vary from one brand to another. It’s good practice to keep using a forward facing child car seats for as long as possible before transitioning to a booster. Look for seats that have taller backs which can be used longer when you’re buying.

Child booster seat use diagram

Moving from a booster seat into an adult seatbelt

When our babies are little, we tend to err on the side of caution. This is in stark contrast to years later at the booster or seatbelt stage when safety is often not given as much consideration as convenience. They’re not our fragile babies anymore. They may protest with claims of being a big boy or girl, they’re likely to have started school and may even compare themselves to their friends.

Using an adult seatbelt is not a rite of passage. It’s about safety and safety is not based on age.

Remember child car seats 101 – the legal minimum and what is recommended as safe is usually not the same. While the law tells us the legal minimum age, to keep our children safe we need take into consideration how tall they are.

Adult seatbelts are designed for people who are at least 145cm tall.  Less than 2% of 7 year old children are 145cm tall

Children have the best chance of getting the right seatbelt fit if they only start using a seatbelt when they’ve out grown their booster seat. This may not happen until they’re 8, 9 or even 10 years old. This is why experts recommend that children should be about 145cm tall before they start using an adult seatbelt.

5 steps to travelling safely in an adult seatbelt

Remember that seats will vary from car to car. In addition, the middle seat may offer a better fit than the outside seats so it’s worth checking what seating position is best for your child. Stick to the second row too. It’s safest for children to stay out of the front seat until they are older than 12 years of age.

Work out if your child can move from a car seat to an adult seatbelt with the 5 step test
  1. Check that your child has their back flat against the back of the seat
  2. Their legs should be able to bend over the seat edge
  3. The seatbelt should run over the middle of the child’s shoulder and not dig into their neck
  4. The seatbelt should sit low and firm across the child’s hips and touch their thighs
  5. This position should be a comfortable sitting position for the whole trip.
Infographic to assess child seatbelt readiness