A lot of rumors have floated around about Miley Cyrus getting a boob job. The way she wears her tops certainly makes it look like she did, but this is Hollywood folks. Also, let's keep in mind that Miley Cyrus was born on November 23, 1992, so most of her physical transformation can be attributed to growing up. At age 21, her breast size is listed at 34B (which isn't as big as they look). This before and after photo shows her looking flat chested in the middle. If she actually had breast implants, her breast size was increased by a cup.