A generalized formulation to characterize droplet size distributions in sprays is proposed. The methodology is based on the Pearson system of frequency curves and on experimental data from different liquid atomizers available in the open literature. The method demonstrated that droplet size distributions in sprays were restricted to the Pearson type I and type VI curves, respectively, called beta and beta prime distributions. It was also verified that the Pearson type III could be used as a simplified model for liquid atomization systems with accuracy comparable to the Nukiyama-Tanasawa distribution. Pearson type III is the so-called gamma distribution, and it is a transition curve between Pearson type I and type VI. As part of this study, random generation of initial droplet size distribution in the spray, following a beta distribution, was used as a boundary condition in the air-blast atomization model implemented in FLUENT (R) V6.2.16, and the evolution of a spray produced by a commercial atomizer was evaluated. The nozzle used in the study was the air-assist atomizer model BETE XAPR-200, which provides a solid-cone spray. For the simulations, the grid was generated with the meshing software Gambit (R) V2.0.4. Very good agreement was obtained between experimental and numerical values.