Recent improvements in computer capacity and technology allow models to be built to simulate the attributes of many agricultural processes and systems. Although Brachiaria brizantha is the most cultivated tropical grass species in Brazil, there is no single tool to predict its production under optimal conditions. The objective of this paper is to present PPBB_MX software to calibrate and simulate (using a stochastical procedure) the shoot and total biomass potential productivity (output variables) of Brachiaria brizantha as a function of the following input variables: local latitude, season (from cutting date - Julian day), length of regrowth (time, days) and climate attributes (global solar radiation and air temperature)
