Tibia fractures account for the majority of lower extremity injuries during pedestrian-vehicle interactions. Skeletal development, adaptation and degradation vary throughout the lifespan of males compared to females, underpinning sex-specific responses to loading. The purpose of this study is to quantify sex differences in tibia cortical bone morphometrics as they relate to age and body size. Quantitative computed tomography (QCT) analyses were performed on 128 cadaveric ex vivo tibia. Total area (Tt.Ar), cortical area (Ct.Ar), cortical thickness (Ct.Th), robustness (Tt.Ar/Le), area moment of inertia (I), and volumetric bone mineral density (vBMD) were quantified. Males had significantly larger morphometrics throughout the tibia (p<0.005), with the exception of vBMD (p>0.17). Sex-specific linear regressions demonstrated varying patterns between males and female with age. Female tibiae were more sensitive to mass as all morphometrics increased significantly (p<0.01) with body mass, with the exception of Ct.Th and vBMD. Body size was unable to predict male morphometrics, with the exception of proximal Ct.Ar and vBMD. Differential patterns in tibia parameters and sex-specific effects of age and body size suggest these should be accounted for in injury risk predictions rather than simply scaling male data to represent females.