Background Several studies indicate that static foot posture bears a low relevance to dynamic foot alignment during walking. Thus, dynamic alignment assessment capable of being utilized in a clinical practice is required for an accurate estimation of foot function. This study aimed to examine the validity of two-dimensional analysis using a tablet computer for estimation of foot alignment during walking, by making a comparison with a motion capture system and static foot alignment screenings.Methods Validity of two-dimensional (2D) analysis of foot alignment during walking using a tablet computer, by making a comparison with a motion capture system and static screenings in healthy subjects. Fourteen healthy males and 15 healthy females participated in this study. Arch height of the right foot while walking was measured using a tablet computer and a motion capture system simultaneously. Arch height at the mid-stance (Mst) and pre-swing (PSw) phase were calculated from kinematic data measured by the tablet computer and motion analysis system, respectively. Static foot alignment also was assessed through the use of a screening test including arch height index and foot posture index. To examine the validity of foot assessment using 2D analysis, we conducted correlation analysis between the arch height at Mst and PSw as measured by a tablet computer and a motion capture system. Meanwhile, FPI and AHI were used to test the relation to arch height at Mst as measured by a motion capture system.Results Arch height, as measured by the motion capture system, showed a significant correlation with that measured using a tablet computer at Mst (r = 0.90, p < 0.001) and PSw (r = 0.94, p < 0.001), and arch height index (r = 0.50, p = 0.005), especially the former. Meanwhile, foot posture index (r = − 0.34, p = 0.075) showed no relation to arch height as measured by the motion capture system.Conclusion These results demonstrate the high validity of 2D analysis using a tablet computer for estimation of foot alignment during walking. Such gait analysis can be effective in assessing dynamic foot alignment in clinical practice.