<p>Isothermal heat flow calorimetry is a valuable characterization method for cementitious materials. Although the method is very precise, it is mostly employed qualitatively, i.e., by visual comparison of individual curves in cementitious systems. Here, we present a computer program implemented in Python that facilitates the quantitative determination of characteristic kinetic parameters for a large number (hundreds to thousands) of calorimetry experiments. The usefulness and correctness of the method are demonstrated by the quantitative evaluation of the concentration-dependent influence of three different cement retarders on Portland cement hydration. We find that for the set of sucrose, etidronic acid, and tartaric acid, sucrose causes the strongest retardation of the main hydration reaction. All three retarders exhibit an exponential relationship between the duration of the dormant period and the dosage of the retarder.</p>