The development of new materials showing the magneto-caloric effect (MCE) requires fast and reliable characterization methods. For this purpose, a phenomenological model developed by M. A. Hamad has proven to be a useful tool to predict the magnetocaloric properties (the isothermal magnetic entropy change, ΔSM, the magnetization-related change of the specific heat, ΔCP,H, and the relative cooling power, RCP) via calculation from magnetization measurements as a function of temperature, M(T). However, fitting the M(T) data is difficult for broad, smoothed-out transition curves which are often observed for material systems such as core-shell nanoparticles, nanowires, nanowire fabrics or nanoparticle hybrid materials. Thus, in this contribution we present a different approach enabling proper fitting of such magnetization data via the use of the asymmetric Boltzmann sigmoid function. As examples, we present fits to M(T) curves of polycrystalline, bulk La0.67Ba0.33MnO3 as well as La1-xSrxMnO3 (x = 0.2, 0.3, 0.4) and La0.7Ca0.3MnO3 nanostructured materials from various authors.