Existing manuals do not provide clear specifications for the required crosswalk width under different pedestrian demand volumes and characteristics. However, optimizing crosswalk configurations including width is an important concern to improve the overall performance of signalized intersections. The objective of this paper is to develop a methodology for estimating minimum required crosswalk width at different pedestrian demand volumes considering bi-directional flow and different pedestrian age groups. The developed methodology is based on modeling total pedestrian platoon crossing time which consists of discharge and crossing times. Discharge time is modeled by using shockwave theory while crossing time is modeled by applying aerodynamic drag theory. The developed models are then calibrated for crosswalks with mainly elderly or pupil pedestrian platoons. A set of criteria based on pedestrian crossing speed is developed to identify the minimum required crosswalk width. Finally, different required crosswalk widths are proposed for different pedestrian demand volumes and directional split ratios considering the effects of pupil and elderly pedestrian platoons.