Grouting operations are widely used to reduce leakage and increase the strength and consolidation of jointed rock in construction sites. One key challenge in these operations is accurately estimating the volume of cement slurry required. Precise estimation enables the grouting process to be optimized both technically and economically, and it also allows for predicting grout penetration in sections with similar conditions based on the results. This research focuses on estimating the cement slurry volume using both analytical and numerical models. Five analytical models are introduced, each assuming the presence of a joint with a constant aperture bb, and calculating the penetration volume accordingly. For numerical modeling, UDEC software was employed. In this approach, the cross-section of the block, the borehole, and the grouting joint were modeled, followed by the application of grout properties and the ultimate grouting pressure. Geotechnical and grouting data from the Seymareh Dam site were used as a case study. To validate the models, statistical analyses were conducted under varying conditions of rock quality factor and grouting section depth. Based on the overall results, analytical model number 4 demonstrated the best accuracy in estimating grout volume, while model number 5 showed the weakest performance. Therefore, if a single model is to be selected, model number 4 is recommended.