Fine-sand soils cannot support the design loads due to their low load-bearing capacity. Soil reinforcement with geogrid-layers is a common technique to increase the low bearing capacity of fine-sand. Using the commercial finite element analysis package Abaqus (Ver. 2017), a three-dimensional numerical model is used to determine the effect of geogrid-aperture size on the square footing bearing capacity of geogrid-reinforced fine-sand. In the numerical analysis, the geogrid-aperture size ratio ranged from 1.0 to 4.0. These variations in the geogrid-aperture size ratio were used to estimate the effect of first geogrid-layer depth (u/B), geogrid-layer width (b/B), vertical spacing between geogrid-layers (h/B), and the geogrid-layers number (N) on the bearing capacity ratio (BCR) and the horizontal stress ratio (HSR), which were transferred to the fine-sand through geogrid-layers. The bearing capacity of a square footing on geogrid-reinforced fine-sand increases with inclusion of a geogrid-layer, provided it has the appropriate dimensions and numbers. The horizontal stresses transferred to the fine-sand through the geogrid-layers also increased. The results indicate that the interlocking between fine-sand and the geogrid-layers increases due to the reduced movement of fine-sand particles. For the variation of geogrid-aperture size ratio from 1.0 to 4.0, the maximum decrease rates of the (BCR), HSR-(Cross), and HSR-(Machine) values are 12.06%, 15.25%, and 18.22%, respectively. The optimal values of (u/B), (b/B), (h/B) and (N) are 0.3, 3.0, 0.15, and 3.0 for all values of geogrid-aperture size ratio. For the maximum (BCR) values of the square footing on fine-sand, using a biaxial geogrid-layer is considered more efficient than using a uniaxial geogrid-layer.