An important step in terms of noise and strength optimization of a gear pair is the optimal design of the micro-geometry.Thereby a combination of various profile modifications is usually used. Since these profile corrections, however, can be in negative interaction with each other, their combination had to be carefully and with great effort tested and verified by the designer. A fine sizing module is now available in KISSsoft which-similar to fine sizing of the macro-geometry- performs the optimization of the micro-geometry in a variant calculation (module ZA33). This process allows to simultaneously evaluate different combinations of profile corrections on several definable load stages. The user decides afterwards, based on various criteria (e.g. face load factor KHβ, transmission error, etc.) and his experience which modification to apply.