This article goes through several steps in order to deliver a reliable result, according to the ASME method, of a shaft dimensioning, aiming to automate the calculation memorial process for shaft projects. The design steps are: stress diagrams, fatigue and geometry analysis (if necessary); correction due to discontinuity (if any); shaft diameter correction due to keyway (if any); and correction due to manufacturer’s selected bearing support (adopting SKF models). In this way, the article aims, in order to comply with the literature and standards, to dimension transmission shafts. The results of the exercises solved in the book Projeto de Máquinas: Uma abordagem integrada will be used as a reference. The developed program aims to meet both professional and academic demands by optimizing the calculations to obtain the diameter of a shaft. In addition, the project is justified by the fact that it allows several changes for a better understanding, either for a designer or for a student. The software used to automate the processes and obtain the results will be Mathcad Prime 5.0 from PTC Enterprise. At the end of the article, along with the results and conclusion, there are examples of design problems solved by the program, along with their explanations and comparisons with the results obtained in the Norton’s book.