A measurement system is described for determining the varus and/or valgus angles of a pronating and/or supinating foot, especially when the subtalar joint of the foot is placed and/or maintained in a neutral position. When the user's foot is maintained in the subtalar joint neutral position, it causes a substantially hemispherically shaped platform member to rotate relative to a correspondingly shaped depression formed in a base portion such that a top surface of the platform member is no longer in a coplanar relationship with a top surface of the base portion. When this occurs, a bottom surface of the platform member is exposed. As a result, indicia are exposed which correspond to degree markings disposed on the bottom surface of the platform member. The degree markings indicate the angle that corresponds to the amount of pronation and/or supination of the user's foot.