We analyzed resistive switching-based memristors by using the charge–flux relations instead of the traditional current–voltage approach. We employed simulated and experimental data to develop a model that can be easily included in circuit simulators. Physical simulations of devices with different conductive filament sizes were employed to fit the 3-parameter model introduced. Later on, the relations between the model parameters and the conductive filament geometrical features were characterized in-depth. In addition, a model to obtain the energy employed in the reset process was presented. Finally, we used the model to estimate the experimental conductive filament radius distribution using a set of 3000 reset cycles. Copyright © 2017 John Wiley & Sons, Ltd.