In core logging, each joint set intersects borehole into some segments. In this research, it has been shown that length of the borehole segments created by each joint set could be computed by trigonometrical relations. By realizing the lengths associated with joint sets, an algorithm has been designed to compute the length of borehole pieces (created by all joint sets) and to calculate RQD. Effect of some factors have been analyzed and applied to the abstract model of the rock mass to have the most similarity to a real rock mass. The program proposed in this study, is a robust platform to calculate the RQD in all directions inside a rock mass without having to deal with the labor of core logging and wrestling with difficulties and inaccuracies of the traditional processes. This is the first algorithmic method for estimating the rock quality which could be employed to develop a new and far more reliable measurement for the degree of jointing inside a rock mass. In this research, it has been shown that length of the borehole segments created by each joint set could be computed by trigonometrical relations. By realizing the lengths associated with joint sets, an algorithm has been designed to compute the length of borehole pieces (created by all joint sets) and to calculate RQD. Effect of some factors have been analyzed and applied to the abstract model of the rock mass to have the most similarity to a real rock mass. The program proposed in this study, is a robust platform to calculate the RQD in all directions inside a rock mass without having to deal with the labor of core logging and wrestling with difficulties and inaccuracies of the traditional processes. This is the first algorithmic method for estimating the rock quality which could be employed to develop a new and far more reliable measurement for the degree of jointing inside a rock mass.