Flatfoot is a well-known foot deformity and is generally evaluated by clinical measurements (Foot Posture Index [FPI-6]) and radiographic measurements. However, these measurements have some limitations, such as a dependence on the examiner skill and versatility. We therefore examined whether or not foot shape indexes for assessing flatfoot are more useful than radiographic measurements. A total of 208 feet from 104 adult women with foot diseases were measured by a three-dimensional (3D) foot scanner to evaluate the radiographic appearance. The heel angle, leg heel angle, arch height ratio, medial arch angle, instep angle, medial protrusion area, heel center angle and curve angle were extracted from 3D foot scans and referenced against the FPI-6 to determine foot shape indexes. Foot shape indexes in the sagittal plane were found to have a strong correlation with the radiographic indexes (r=0.558～0.813, p<0.01). The medial arch angle was particularly notable, and a recipient operating characteristic analysis demonstrated that its area under the curve was 0.867 (p<0.01), and its cut-off value with 87.9% sensitivity and 76.7% specificity was 29.66. In addition, significant correlations were confirmed in the frontal and horizontal planes (r=0.216～0.625, p<0.01). These findings led to the conclusion that these eight foot shape indexes were useful scales for assessing flatfoot.