Choosing the right implant size for a specific patient is a challenging aspect of breast augmentation. Bust circumference is obtained by measuring the chest circumference at the level of the nipple-areola complex. Pre- and postoperative bust circumference measurements obtained from 147 patients who underwent primary bilateral breast augmentation using round, textured, gel-filled implants were evaluated, and a practical reference list for future operations was developed. According to the results, each additional 100 ml in implant size yielded an approximate 2-cm increase in bust circumference. The authors believe these results gathered from systematic measurements may serve as a useful guide for choosing the right size implant for a satisfactory augmentation procedure.