What are the signs for growing out of Stage 1 car seat?

[Murtette]

DD is 3.9 but slight for her age so is only just over 15kg. Due to weight, I hadn't been thinking about moving her into a stage 2-3 for a good while yet but noticed today that she's looking quite tall for it as the crown of her head is well above the top of it and her eyes are getting close to the top of it too. Do the same "rules" apply for moving out of group 1 car seats as apply for group 0+ car seats?
Thanks

when their ears/eyes are at the top of the seat then they are too tall for it and should move to the next stage seat. The next stage seats are suitable from 15kgs.

Thanks. I think its time to order DD a new car seat.

I would hold off for a few months whilst she eyes aren't level with seat.

15kg is the minimum weight the seat belt will lock in place and children can lose weight when ill etc.

Maybe consider a Britax evolva which will harness her til 18kg and has a higher shell as it then converts into a booster seat.