<p>Blasting in sandstone rock mass widely exists in tunneling and mining engineering. In this study, the rock fragmentation and energy dissipation under sandstone blasting are experimentally and numerically investigated with the variation in powder factor (0.188–0.983&#xa0;kg/m³). Six tests of blast-induced rock fragmentation are conducted using sandstone cylinders with dimensions of 200&#xa0;mm in diameter and 200&#xa0;mm in height. The blast-induced fragment size distributions (FSDs) are quantitatively analyzed through sieving and curve fitting. Then, the fragment geometry, including fragment size and fragment shape, is further examined via image processing, and the energy dissipation in sandstone fragmentation is calculated based on Griffith fracture theory. Furthermore, the disintegration of sandstone cylinder and associated energy consumption during blasting are modeled in LS–DYNA. The physical tests show that the rock fragmentation shifts finer and uniform as the charging density increases, leading to a significant proportion reduction in large fragments and a prominent increment in small and fine fragments. The blast-produced FSD can be well-characterized by Weibull distribution, three-parameter GEV function and extended Swebrec function, with the latter demonstrating superior accuracy in capturing both fine and coarse fragments. Meanwhile, the fragment shape becomes rounder first and then changes to more elongated. During blasting, the sandstone cylinder fracturing consumes 6.69–14.00% of the explosive energy. In addition, the current simulation is in good agreement with physical tests and shows that the internal-to-kinetic energy ratio of rock decreases, while the transfer efficiency of explosive energy into internal energy increases with the increased charging density. In the current sandstone blasting, the efficiency of utilizing explosive energy in rock fragmentation has the optimal specific charge of 0.665&#xa0;kg/m³.</p>