How old does a child have to be and weigh to use a regular seat belt and booster seat?

Rear facing at 6, wow

My 6 year old weights around 38 lbs. She's in the extend to fit, still rear-facing so in a 5 point harness. My boys are 3 and 4 and also in the same seats.

Regardless of when they say it can be used it is highly recommended to use a harness until 5. Their bones are not ready for it before then. By 5 they should meet the limits anyways but some kids still aren't mature enough to sit still at 5 and have to be in one longer.

My girl has a 5 point harness . It turns into a booster. I'll stick with the 5 point harness for at least another year.

Honestly some booster seats have pretty low starting limits which makes no sense to me. Look into harness to booster seats so you can use the five point harness longer.

Yes I'll look

I think your convertible car seat says when to use the seatbelt and booster seat option

@mokimbo thanks.

https://csftl.org/harness-or-booster/