We have developed an advanced inversion charge model for both n-type and p-type symmetrical Double-Gate MOSFETs where quantum mechanical effects (QMEs) have been included. By doing so, the role of different crystallographic orientations was successfully taken into account. Self-consistent Poisson and Schrodinger simulators were used to check the accuracy of the model presented. As a starting point, a classical inversion charge centroid model was considered. Afterwards, an inversion charge model was developed including QMEs by means of a corrected oxide capacitance. The validity of the model was checked for the three common wafer orientations (100), (110) and (111) and for devices with different silicon layer (t(si)) and oxide (t(ox)) thicknesses. As it will be shown, the model reproduces correctly the simulation data both in the subthreshold and in the strong inversion operation regime. (C) 2011 Elsevier Ltd. All rights reserved.