Abstract Usually, the exact geometry of the blank of a stamping is obtained by successive corrections of a presupposed blank subjected to the operation of stamping or its simulation. This paper presents an innovating method of direct predetermination of the blank. The part is set flat that it gives the required part when subjected to the action of the tool for stamping. The setting flat presents splits and the part carried out some discontinuities. The setting flat is then deformed to reabsorb the splits and the shape thus obtained is the optimized blank. This method is illustrated and validated on a rectangular cup by a comparison between the calculated blank and the part obtained.