AbstractParticle size effects constitute a major source of error in the x‐ray fluorescence of granular material. Different models have been proposed to account for the influence of particle size on the characteristic x‐ray intensity leaving the sample. Important points in these models are the granular distribution from each grain. Berryet al.proposed a model which is in reasonable agreement with experimental values. In this work, fluorescent intensity calculations for a cubic particle with different geometries were carried out. The intensity values obtained through this model were compared with the Berryet al.model. There is better agreement with the experimental values when the expression obtained is used in order to find the total fluorescent intensity using heterogeneous samples consisting of fluorescent and non‐fluorescent components of particle