The aim of this study is to formulate a criterion to describe the onset of splashing for dilute and dense suspension drops composed of hydrophilic or hydrophobic particles. The formulation is based on the analysis of the existing data from the literature and from us. The new criterion improves upon current models in predicting the splashing threshold by introducing effect of particle volume fraction and particle wettability. The criterion's mathematical formulation correctly describes the dependence of splashing on particle diameter, volume fraction, and wettability. It works equally well for predicting the onset of splashing on hydrophilic and hydrophobic substrates.