Its depend upon their body type..
I am a 11 year old girl and I have no boobs. So really the average size is none. I only have breast buds.
32A or 34A would be average bra size for a 12 year old girl.
34
34B
b or c
Breast size varies greatly among individuals, so there is no definitive average breast size for an 18-year-old. Factors such as genetics, body weight, and hormonal influences can all impact breast size. It is important to remember that everyone's body is unique and there is no standard or "normal" breast size.
1 cm
Id say anywhere from 30A-36B
The average size is a 32 A or 34 A but if you are bigger or smaller its just how your body is growing
Untill a women gets to around about 20 there is no average size as all humans carry on growing until roughly then.
It hard to say but i would say around 32 -36
I think that a 16 year old girl's breast areola size should be around a size 16