Computer programs have been used to help the farmers on the fleet selection. However, these computing models are based on the previous choice of the mechanized system made by the user. On this context, the purpose of this work was to develop a free computer model by a linear program and via internet to select agricultural mechanized systems based on the smallest operational cost, bringing the machinery selection process more agility and confidence according to a farm needs. The software can be accessed over the internet where the user can select an agricultural machine within a vast machinery list which contains its technical specification, as well as can help the farmer informing him automatically about the system with the smallest cost.  The huge advantage of this program is that it is free and can be easily kept by the developer, once the data base is installed on a computer server and it is not needed to be installed on the user computer.