Abstract.The study in electric field distribution in the space by different charged geometries, allows to improve the designs of the devices used in electrical engineering. In this work the capacities of a charged unit cube by two different methods have been calculated by means of technical of finite element analysis. Firstly infinite elements in the air that surrounds the charged unit cube were considered, and secondly the conditions of contour of the Trefftz method were used. The proposed models has been achieved to calculate the capacitance of a unit cube based on the size of the element.