India ranks second after the United States in terms of road infrastructure. In recent years, geosynthetics have created an impact on enhancing the life of the pavement. Numerous studies have been done on the application of geosynthetics on the flexible pavement to reduce rutting deformations and fatigue cracks. Laboratory and field studies have cost and time constraints. These limitations can be overcome by making use of numerical models. This research focuses on the numerical analysis of biaxial geogrids in flexible pavement. Proper knowledge of geogrid-pavement layer interaction is essential to obtain an understanding of strains, stresses, and deflections in pavement layers. In this study, a three-dimensional model of the geogrid reinforced unpaved road is developed using the finite difference program -FLAC 3D . Appropriate constitutive models are selected for the pavement layers. Geogrid is modeled using a linear elastic 'geogrid' element in FLAC 3D . The thickness of pavement layers in the analysis is taken as per the codal provisions of IRC: 37-2012. For pavements underlain by weak subgrade, the study shows that geogrid is more efficient in resisting the loads for settlement ratios higher than 2%. Based on the results from the numerical model, the optimal location of geogrid is proposed at one-third base thickness from the top of the surface of the pavement. This study is useful for construction sites where competent aggregates are not available and subgrade CBR is less than 5%.