There is no specific bust size for a size 18 woman. The average bust size for a size 18 woman is 109 cm/43 in.
What dress size is for a thirty inch bust
34I in U.S. sizes
Kooiman has never publically announced her bust size.
a 30a bust is tiny usually in a child who is starting to mature
it means the size of your boobs
A 30A is a rather rare bra size, as it means the ribcage equals 30 inches and the bust equals 31 inches, since an "A cup" only means there is a one inch difference between the ribcage and the bust. Because of that, an A cup on different bands will be a different size-a 36A would be for someone whose ribcage equals 36 inches and their bust 37, a 26A would be for someone whose ribcage equals 26 inches and their bust 27, et al. Since an A cup marks a one inch difference, yes, a 30A is a small bra size. There is a very good change you have been fitted incorrectly though, possibly with the "Plus 4" method, which spawned "The War on Plus 4". You may be more like a 26DD, which means your ribcage equals 26 inches and your bust equals 31 inches, marking a 5 inch difference, which equals a DD.
by having sex