In the construction in series of mechanical parts is essential to ensuring the interchangeability of the various details, what is required, in the series of a certain machine, that each copy of a given key can not mate with the same mode (free, sliding, etc. locked. ) within each copy of the corresponding hole. For this reason there are dimensional tolerances. Tolerances Calculator is an app that helps, precisely, to calculate the scraps of a dimensionless value (difference between the maximum size and the minimum size eligible) of a mechanical piece between 1mm and 3150mm. This app is designed for drafters, echanical and operators of CNC machine tools. There are all values of degrees of tolerance IT (1 to 18) and all deviations for bores and shafts (from A to ZC).