Screenout of micro-proppants in narrow fractures is a significant issue for this emerging stimulation technique, however the predictive tools currently used in hydraulic fracturing simulators are inadequate. This work investigates screenout using numerical simulations. Data from the numerical test cell is translated to regions of screenout, which are dependent on the proppant solid volume fraction, ø, and the ratio of fracture width to proppant diameter, w/d. The dependence on w/d which is demonstrated is commensurate with existing bridging modelling. The method of numerical simulation, however, allows further insight into the underlying mechanisms of screenout, namely collision frequency and bridge stability. Incorporation of the screenout regions into a hydraulic fracturing simulator significantly improves the current industry standard of using a threshold of w/d = 2.5, at similar computational cost during the hydraulic fracture simulation. The screenout regions can be readily reproduced for any desired modification of parameters, such as friction, by modifying the numerical simulations. This is done here in the presence of electrostatics, and is the first time a methodology has been presented which can incorporate electrostatic parameters into screenout predictions of hydraulic fracturing simulators. Overall, the methodology significantly improves the efficacy of screenout predictions by considering the underlying parameters.