A method of determining input pattern is adapted to be implemented on an electronic apparatus equipped with a touch panel and includes the steps of: detecting a plurality of boundary points between an input pattern inputted through the touch panel and a circumscribed polygon of the input pattern, detecting an area ratio of a polygon defined by the boundary points to the circumscribed polygon, and determining the shape of the input pattern at least according to the area ratio. The present invention also provides a computer readable storage medium having a program stored therein. When the program is executed which enables an electronic apparatus equipped with a touch panel to determine the shape and/or direction of an input pattern inputted through the touch panel.