The domestic windows in the exterior building facade play a significant role in sound insulation against outdoor airborne noise. The prediction of their acoustic performances is classically carried out in laboratory according to standard ISO 10140. In this work, a 3D elasto-acoustic finite element model (FEM) is proposed to predict the sound reduction index of three different glazing configurations of domestic window follows the ISO recommendations for acoustic measurements, which are compared to laboratory measurements. Two acoustic cavities with rigid-boundaries on both sides of the window are used to simulate respectively the diffuse sound field on the source side and the pressure field on the receiver one. By using a simplified FEM for the double-glazed windows, the sound reduction index is calculated from the difference between the source and receiving sound pressure levels in the one-third octave band from 100 to 500 Hz. Although the comparison between numerical and experimental results shows a relatively good agreement which highlights the interest of this kind of approaches to avoid expensive experiments, many improvements should be taken to ameliorate the model such as the different components of the frame and the design of the two rooms to avoid the problematic of multi-resonant frequency ranges.