Vickers hardness (H V ) from elastic properties was evaluated using the empirical Mazhnik-Oganov and Chen-Niu models. Hardness was also estimated in the framework of the thermodynamic model , which is based on thermodynamic properties and crystal structure, and using the Lyakhov-Oganov approach , which takes into account the topology of the crystal structure, the strength of covalent bonds, the degree of ionicity, and directionality. Fracture toughness (K Ic ) was evaluated using the Mazhnik-Oganov model . Table summarizes the Vickers hardness values for all considered crb boron pnictides calculated using four models. A tendency of a significant decrease in hardness with increasing atomic number of the pnictogen is observed for all four models. Since it has been shown earlier that the thermodynamic model is the most reliable in the case of boron compounds and shows perfect agreement with the available experimental data for boron pnictides , it is obvious that the hardness values calculated within the empirical models are strongly underestimated. The Oganov-Lyakhov model gives slightly underestimated values for compounds of light pnictogens and does not work in the case of BSb and BBi. It should be noted that all crb phases exhibit 4-7% less hardness than other BX polymorphs due to the increased openness of the crystal structures. However, all crb boron pnictides are hard phases with Vickers hardness exceeding that of cemented tungsten carbide, the conventional hard material.