Hi there...as others have noted that most cats on average will reach full growing potential at 18 months--Bengals are no exception. However some, not all will begin to fill out width-wise up to 3 years of age. Depending on the pedigree each Bengal some will be either bigger or smaller even than their litter mates. For example my Bengal's father and his brothers were huge at 9 months...weighing in at 12 pounds, yet my boy was 4 pounds less than they were. Some Bengals are taller and longer than others as well even within the same family--my Bengal boy is very long and tall, but his brothers are more stocky and short like their father. Again, it all depends on the pedigree characteristics of the parents and grandparents as well as littermates.
Animal Trainer to domestic and exotic cats
Owner & Rescuer of Bengal Cats (see avatar)