Brittleness is an important rock property that examines the mechanical behavior and failure properties of rocks in engineering applications. Although there is no standard method for measuring rock brittleness, it can be calculated indirectly as a function of rock mechanical properties based on the rock strength ratio. The aim of this study was to investigate the relationship between the Leeb hardness (HL) values and the brittleness properties of rocks using the simple statistical method. For this purpose, 18 sandstone rock samples were collected and tested in the laboratory to determine the HL and physico-mechanical properties of rocks. In addition, the brittleness properties of rocks were examined with S20 brittleness (BI8) test and five different empirical methods (BI4, BI5, BI11, BI13, and BI14) calculated from rock strength ratios. New models were proposed to predict the brittleness of the rocks, taking into account the HL. Based on the statistical analysis, the proposed models were in good agreement with those measured (for all of the data, R-2: 0.76-0.77, for sandstone, R-2: 0.78-0.81).