Stochastic, especially simulation, occasionally could be found in different geological calculations, mostly as the most advanced mapping method. Its main attribute is description of uncertainties that are inherent not only to any geological mapping dataset but also to any volumetric or probability calculation. Here are presented uncertainties in all three cases – mapping, volume calculation and probability calculation – and reasons why and when to use stochastic in them. The stochastic, and consequently simulation, is a recommended tool in case of a low number of data (<15 inputs) or large dataset (>40 inputs), but in both cases, the descriptive statistics needs to be known and is reliable. Almost the same could be applied in volumetric calculation, but the success of stochastic in probability calculation depends on large datasets, with 15 or more inputs.