An inflatable packing element for a bridge plug. The packing element has an anchor portion and a sealing cover portion, each of which is expanded in order to engage and seal a surrounding string of casing or borehole. The anchor portion has a minimum length defined by 2.63× the inner diameter of the surrounding pipe or other wellbore opening. At the same time, the anchor portion has a maximum length defined by approximately 49% of the length of the expanded portion of the packing element engaging the surrounding pipe or other wellbore opening.