A statistical regression analysis was conducted on 146 selected test results from the literature to evaluate the basic ACI318 two-way shear strength equation, which has not changed since 1963. The basic ACI318 shear equation was established based on a statistical analysis of test results on scaled slab samples that were believed to have failed in shear. Only slabs with square columns, sheared on four sides and without shear reinforcement were needed in this study, resulting in 146 selected test results from 1956 to 2014. The study included slabs with normal and high strength concrete. This study presents new equations for slab punching shear capacity. The effect of several parameters on the punching shear strength is also discussed in this study. A simplified practical punching shear equation is also proposed based on statistical analysis of the experimental results from the database. The new proposed equations include the reinforcement ratio of the slab and the cubic root of the concrete strength. The study also showed that including the reinforcement ratio in the punching shear equation increases its accuracy. The new proposed equations are valid for normal and high strength concrete slabs.