This study examines the prevalence of anatomic variation and asymmetry in female thoracic contour and evaluates their effect on breast projection. A consecutive series of 50 female cross-sectional thoracic computed tomography (CT) scans was examined at the level of the fourth rib. Patients with thoracic wall trauma (including surgery) were excluded. Lateral width, anterior-posterior diameter, and 3 internal angles were compared bilaterally and were used to evaluate overall shape and thoracic contour. All patients demonstrated some degree of asymmetry between their right and left sides. A wide range of thoracic shapes was observed. Patients with sloped anterior chest walls have lateral projection of the nipple, while patients with flatter chest walls have anterior projection of the nipple. Evaluating anterior chest wall slope prior to augmentation can help physicians predict postoperative breast projection and thus prepare their patients for the future breast appearance and the potential for contact cleavage.