Boosting Safety

Your child is unable to properly fit an adult seat and seatbelt until they are at least 148cms tall. Until then, it is far safer to use a booster seat. Find out how this can save your child from serious injury in the event of a crash.

Every year, on average, 20 children in New Zealand are killed while passengers in motor vehicles and over 260 children, aged 14-years or younger, are injured severely enough to be hospitalised. This is the equivalent of five children being killed or injured every week.

By law in New Zealand, all children under 5 years of age must use a child car restraint that is appropriate for their weight and size when travelling in a vehicle. A seat belt on its own is not enough. As a general rule, if your child’s head is higher than the back of the child restraint when seated (i.e., carseat), it is time to move him into the next type of child restraint (i.e., booster seat).

Booster seats are designed for children who no longer fit in a car seat, but are too small to correctly fit an adult seat belt. Because of a child’s smaller size and unique proportions, they do not fit standard seats and belts designed for adults. Children require a booster seat to enable them to fit the seat belt correctly and to gain the full safety benefit of the seat belt, in the event of a crash.

Without a booster seat, an adult seat belt sits too high on a child, ending up around their neck or face or across their tummy. This can cause injuries to their neck, throat and abdomen in an accident.

In addition to the safety element, booster seats also elevate your child higher so that they can see better out of the window, which is much more pleasurable for them and you, especially on a long journey!

While most parents are aware that putting children in the back seat is far safer than letting them sit in the front, what is less clear is up until what age is safest to keep them in a booster seat. Most children don’t fit adult seatbelts properly until they are 4’ 9” tall (approx 148cm) which is usually between the ages of 8- and 12-years.

The following ‘5 step test’ is a helpful guideline to check whether your child should be using a booster seat:

Step 1. Does your child sit all the way back against the car seat?

Step 2. Do your child’s knees bend comfortably at the edge of the seat?

Step 3. Does the belt cross the shoulder between the neck and arm?

Step 4. Is the lap belt as low as possible, touching the thighs?

Step 5. Can your child stay seated like this for the whole trip?

If you answered ‘no’ to any of these questions, your child requires a booster seat.

As booster seats are designed to work with the car’s lap and shoulder belts, they’re easy to install. The safest place for a booster seat is in the back seat. Simply place the booster on top of the seat so that it sits flat against the car seat – and check it can’t tip over.

You can seek expert assistance from a child restraint technician who can check your car seat is installed correctly and advise about the best car seat for your child’s size and weight, and best suited to your car. Child restraint technicians are available through Plunket’s car seat service, and at a number of other hire outlets or retailers. Plunket offers car seat checks free of charge.

For information on a car seat service near you, visit

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