The use of CubeSat-like small satellites is growing exponentially nowadays, pushing towards missions of increased complexity, including Earth imaging, commercial communications and astronomical observations. As such, they might require components that may survive the re-entry conditions and reach the ground, posing risks for population and properties, or that are intended to be retrieved. The possibility of demise and ground impact poses many challenges from the modeling standpoint because of the uncertainties associated with both the aero- and the aerothermo-dynamic models of the spacecraft. Several formulations and correlations can be found in the literature. Most of them are derived in dated and difficult-to-access papers and technical reports. This paper collects all the necessary and sufficient models, laws and data to describe in a comprehensive way the re-entry of small satellites. They are presented in an organized fashion, with uniform nomenclature and consistent assumptions in order to provide the smallsats scientific community with a smallsats specific, easy-to-understand and rapid-to-implement tool. Furthermore, the paper originally presents an approximated aero- and aerothermo-dynamic model of the Drag De-Orbit Device, a recently developed drag modulation device for drag-based controlled re-entry of large CubeSats.