At what age/weight can a child travel in a car using just the seatbelt?

[Lynswin]

When can I safely do away with child seats and let my children use the seatbelts on their own?

[snick]

The laws says that up to the age of three children should be in a suitable child restraint i.e child seat, in the front of the car. They can use an adult belt in the back if no child seat is available although this is not recommended. From 3-11 they should have on adult belts front and back if no child seat is available or they are too big for one. Essentially once they are over three and too big for your child seat they can use adult belts. We found the booster seats available lift them high enough off the car seat to fit the adult belts safely and comfortably. Hope this helps.