Toner mass transfer in the developer nip, an essential part of the electrophotographic imaging printing process, greatly effects print quality. It has long been known that toner particle size and toner particle charge are the two most important factors impacting toner mass transfer in the developer nip. However, there is no quantitative analysis to help determine the effects of these two factors, nor the interaction between them. A third factor, toner particle packing, also influences mass transfer but is typically not considered due to the lack of an effective metric to describe this packing. In this work, distance between particles is used to approximate this factor. The discrete element method (DEM) model developed in previous paper “Simulating Motion of Toner Using the Discrete Element Method” is used here to study effects of these three factors. All three factors (toner particle size, toner charge, and toner packing), and the relationship between these three factors, were investigated using the DEM model in a design of experiments (DOE) format to understand how they influence toner mass transfer. Factors affecting the pile height on the developer roller after mass transfer and the line-width on the developer roller after mass transfer are the same, however, the effect of these factors are different.