The study is a combination of finite element method and the basic equations of shallow spherical shell to determine the required stiffness of outer surface panel. One finite element model is run and the required stiffness for different thickness or sweep is achieved from the shell equations by numerical iteration. Thus, the many finite element trials required to evaluate the clay surface can be avoided. Iso-stiffness curves are also presented with a direct conversion of panel thickness from steel to aluminum. A computer program for this method has been developed and applied for hoods, deck lids and roofs of various models. It is found that the stiffness results, in general, are satisfactory. In the case of a panel with outboard character lines the center unsupported area shows more accurate results than the outboard area.