As computational models of the human thorax are increasingly utilized to investigate injury risk in car crash scenarios, accurate rib cross‐sectional geometry becomes critical to ensure biofidelity of these models. Cortical thickness (Ct. Th) of ribs has been shown to be an important geometric parameter for obtaining accurate number of fractures, fracture location, and structural properties such as failure displacement and loads [1‐2]. Although many methods have been utilized to explore Ct. Th of human ribs [3‐5], they have been limited by poor resolution of cross‐sectional images, subjectivity and inaccuracy in defining the orientation of Ct. Th lines, and small sample sizes. Therefore, the aim of this study was to establish an objective and accurate methodology for measuring Ct. Th of human ribs from microscopic cross‐sectional images and investigate trends with age.