The extreme size selectivity of the toning process presents a unique challenge of preparing toners with minimal fines. The Coulter Counter technique has been standard for characterizing toners because its ability to discriminate fines levels. The advent of chemically prepared toner with no fines and processes such as multiple classification steps in ground toners has revealed needed improvements in the characterization method. Dispersion stability and count rate were found to have the opposite effects on the measured fines level. A simple modification was discovered that could overcome the artifact of recounting coarse particles as fines due to turbulence inside the aperture tube. Investigation using this modification found that a simple mathematical model with one tuned parameter for each aperture size could be applied to simulate the modification.