When Should My Child Move To A Booster Seat?

Posted by Julie Monson on

When should my child move to a booster seat
Julie Monson


Occupational Therapist &

Certified Car Seat Technician


When your child is close to outgrowing the toddler seat, usually around 4 years, it is time to start considering a booster seat. A toddler car seat harness is outgrown when the maximum weight OR height is reached; whichever comes first. 

For most toddler car seats sold in South Africa, toddler mode (Group I) is outgrown at 18kg or approximately 105cm. Be sure to check your car seat manual, especially if you have a multistage seat to 25 or 36kg, as their Group I (harnessed) weight limit is usually also 18kg maximum.


iSize car seats have defined height limits that will be clearly marked in the manual as well as the orange stocker on the car seat shell. 

Toddler car seats that don't have specified height limits are considered outgrown by height when the straps are at the highest setting but start to dip below the shoulders and/or when the child's eyes are level with the top of the headrest. 

It is not safe to continue using the harness on a child who has reached the height/weight limits, as there is risk of it failing in a crash .


A child needs to be at least 4 years, 15kg and 100cm tall to fit a highback booster safely. These are the MINIMUM requirements in order to fit a booster properly. However, there will be an overlap where your child may still fit in their toddler seat. If this is the case, keep them in their toddler seat until they outgrow it by weight or height. 

A toddler car seat with a 5-point harness distributes crash forces more evenly across the torso when compared to a booster using the 3-point seatbelt. So if your child is still within the maximum weight and height of their toddler car seat, it is best to continue using it until they have outgrown it. 

Although many boosters state that they are approved from 3 years, it is not recommended that children move to boosters until they are at least 4 years old. 

This is because a child's maturity plays a key role in your child being ready to use a booster safety. It is important that a child is able to sit still and upright at all times in a booster, before they are safe to travel in one. 

A booster does not restrain a child like a 5-point harnessed car seat does, which means they have much more freedom to climb out a booster, unbuckle themselves and get themselves into dangerous positions.

booster readiness

If your child is reaching/bending or half out the booster at the time of a crash, they would not be properly restrained by the seatbelt or protected by the shell of the booster. This would place them in a dangerous position and make them more vulnerable to serious injury. 

Once a child has outgrown their harnessed car seat and is booster ready, there isn’t any scientific information that proves that a harness is safer than a properly used booster seat. The key is that the booster must be properly used: where the child is of appropriate age and the belt is positioned properly.

A child is only booster ready when they meet ALL 5 criteria: 

  1. At least 4 years old. 
  2. Meet the weight of 15kg 
  3. Meet the minimum height limit of 100cm 
  4. Be responsible enough to sit properly 100% of the time, even while asleep. 
  5. Have a safe belt fit.



It is not possible to know for sure how your child will cope in a booster until they have sat in one for a couple of weeks. If your child has already started trying to escape from their harnessed toddler seat, that is a clear indicator that they are NOT booster ready and will be best suited to a 25kg harness car seat for longer until they are ready for the responsibility that comes with using a booster seat (explained below in this article)

Ideally, you should start booster training a month or two before your child is likely to outgrow their toddler seat. This gives you adequate time to properly assess whether or not your child is indeed mature enough to cope with the responsibility of traveling in a booster.

Start booster training for short distances in a borrowed highback booster for a few weeks, if you do not yet have one.

It is helpful to buy a small (crash tested) mirror to stick on the windscreen so that you can keep an eye on your child (when the vehicle is stopped and it is safe to do so!). If you find that your child wiggles around, unbuckles themselves, plays with the seatbelt, leans forward or to the side, he/she may not yet be ready for a booster seat.

booster training


Seatbelts are lifesaving devices and have saved countless adults' lives. They are designed to fit and protect adults over 1.5m tall, but can cause severe or even fatal injuries in shorter children. 

Children strapped with just a seatbelt before they are 1.5m in order to achieve a safe seatbelt fit were found to be 3 times more likely to be injured in a crash than adults. 

Children can suffer serious neck and head injuries and perforated intestines when using a seatbelt alone. This pattern of injury has become known as “seat belt syndrome” by doctors who regularly face this pattern of injury in children.

A booster raises a child up on the vehicle bench, in order to get a safer lapbelt fit. The seatbelt guides on highback boosters' headrests also positions the shoulder belt into a safer position across your child's shoulder rather than close to the neck.  For more information on how boosters protect older children, please read our blog article.

How long should MY CHILD use A booster?

Although South African Law does not specify that a child over 3 years should be using a booster seat rather than just a seatbelt, crash testing shows that children between 100-150cm  are MUCH safer in car seats or boosters.

It is therefore recommended that children use boosters until they reach 1.5m and pass the 5-step test. For most children, this is only when they are 10-12 years old.

5 Step Car Seat Test                                                                        Photo credit: The Car Seat Lady


A Safe Seatbelt Fit requires that:

  1. The child's ears should be below the top of the headrest
  2. The seatbelt should be in the guide and positioned just above the shoulder (not cutting in the neck) and even across the torso.
  3. Both portions of seatbelt UNDER the armrest on side closest to buckle
  4. Lap belt should be low and flat across the hips, touching the tops of the thigh NOT over the abdomen
Watch our video below where we demonstrate how to adjust a booster to get the correct fit across your child's body.


Until recently, there were very few, rather expensive options for children who had outgrown toddler seats but were not yet booster ready. Fortunately, manufacturers have brought out more  25kg harnessed toddler car seats. For children who are bigger than average or who are not yet ready to move to a booster, there are 12 car seats that harness to 21-25kg:

  1. BeSafe iZi Plus X1 is rear facing only and installs with seatbelt. It scores “good” for safety on the Swedish Plus Test, which is the most stringent test to pass. Rear facing is safest for children under 4 years old.
  2. Volvo (Britax) Maxway. It is also rear facing only to 25kg. It scores “good” for safety
  3. Axkid Minikid 2 is also rearfacing only up to 25kg or 125cm. It has been Swedish Plus tested (the most stringent crash test to pass). It installs with seatbelt and self-adjusting lower tether anchors.
  4. Axkid One or One Plus is also a rearfacing only seat up to 23kg or 125cm. It is THE ONLY extended rearfacing car seat in the world that installs with isofix only. It was a test winner and scores "good" for safety by ADAC as well as in the Swedish Plus test.
  5. Axkid Move is also rearfacing only up to 25kg or 125cm. It has been Swedish Plus tested (the most stringent crash test to pass). It installs with seatbelt and lower tether anchors.
  6. Axkid Rekid is also rearfacing only up to 25kg or 125cm. It can be installed with isofix and lower tether anchors until 18kg and then must be installed with seatbelt and lower tether anchors until 25kgs. It has also been Swedish Plus tested.
  7. BeSafe Stretch is a rearfacing only seat that installs with seatbelt and lower tether anchors. it can be used up until 25kgs or 125cm (whichever comes first). It has been Swedish Plus Tested and ADAC tested where it scored very well for safety. (COMING SOON)
  8. Cybex Pallas G-iSize is a forward facing seat with an impact shield instead of a 5-point harness. The shield can be used to 21kg/105cm, thereafter it must be converted to a highback booster to 1.5m/50kg. It scores "good" for safety by ADAC. It installs with isofix and top tether anchor.
  9. Cybex Anoris T i-Size is a forward facing seat with an impact shield instead of a 5-point harness. There are airbags in the shield. This seat goes up to 115cm/21kgs which is approx 6 years old for the average sized child. It does not convert to a booster but it scored extremely well for safety in crash testing (even though it is forward facing).
  10. Joie Bold. It forward faces with harness to 25kg then converts to a highback booster to 36kg. It scores “average/satisfactory" for safety It installs with seatbelt, isofix AND top tether anchor, so may not fit all cars.
  11. Safeway Elegance. It forward faces to 25kg then converts to a highback booster to 36kg. No safety reviews available. It installs with seatbelt and top tether anchor, so may not fit all cars. There are no safety reviews available.
  12. Chicco Seat Up 012. It rear faces to 13kg, forward faces to 25kg and booster to 36kg. It scores “average” for safety. It installs with seatbelt and top tether anchor, so may not fit all cars
  13. Safeway Polar. It rear faces to 18kg and forward faces to 25kg then converts to a highback booster to 36kg. No safety reviews available. It installs with isofix, seatbelt and top tether anchor, so may not fit all cars. There are no safety reviews available.
  14. Maxi Cosi Beryl. Rear faces to 13kg and forward faces to 25kg. It installs with isoifix OR seatbelt. It scores average for safety. It can be installed with seatbelt OR isofix.


We sell the highest safety rated boosters at Precious Cargo

Child Booster Seats

Booster Seat Collection

Click the button below to view our collection of the highest safety rated boosters that we sell



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  • To the preciouscargo.co.za administrator, Your posts are always informative and well-explained.

    Benny Dalgleish on

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