The freezing of pharmaceuticals recently has garnered substantial public interest. Storage conditions of COVID-19 vaccines have received global news coverage, since they greatly impact the product's supply chain, with low temperature cold chains being costly or not even available depending on the market. Although the stabilizing effect of freezing has been studied intensely, 5-10 its quantification and prediction remain challenging until today. Numerous studies have confirmed that the stabilization depends not only on the formulation, which includes the active pharmaceutical ingredient (API) and excipients, but also on the process conditions. Freezing comprises two phases, namely a cooling phase, during which the formulation is in the liquid state, and a solidification phase, during which ice is formed. Solidification is initiated by ice nucleation, which is a stochastic process, leading to variability in freezing behavior among vials even if their thermal environment is identical. Based on these considerations, freezing may be characterized by three quantities, which are conceptually linked to most of the known degradation mechanisms for frozen biopharmaceuticals: 7-10, These are the nucleation time, i.e. the duration of the liquid state; the nucleation temperature, which is interpreted as predictor for the ice crystal morphology in the frozen product; and the solidification time, which is the duration of the partially frozen state and connected to the phenomenon of freeze-concentration. In case a drug product exhibits a relevant degradation mechanism related to freezing, these three quantities should be considered during development, implying that all vials meet qualified target ranges with sufficient probability.