when can kids go into a booster seat

In Australia, kids move to a booster seat once they’re at least 4 years old and have outgrown their forward‑facing seat with an inbuilt harness (check the shoulder‑height markers).

From 4 to 7 years, they must use an approved booster or a forward‑facing restraint; the booster should be paired with a properly adjusted lap‑sash belt or child safety harness. After 7, a booster is still recommended until they pass the five‑step test—sit back against the seat, knees at the edge, belt low on hips, sash across shoulder, and no slouching. Age is the legal yardstick, but fit is the safety boss; a too‑big adult belt on a too‑small kid is about as useful as racing slicks in a hailstorm. Wherever possible, under‑7s ride in the back; some states only allow the front if no suitable rear position is available. Always follow your seat’s instructions and your state’s road rules—when in doubt, get a fitting check from an accredited installer.