Many molecular properties of interest (e.g., the likelihood of a molecule to crystallize or flexibilityactivity relationship information derived from NMR data ) are determined by the three-dimensional (3D) structure of molecules. However, at temperatures above absolute zero, most molecular structures are not well described by a single conformation, which makes it necessary to consider a multitude of conformational states. Though intuitive and commonly used, flexibility itself is not easily definable or quantifiable , and different notions have been introduced focusing on the kinetic, thermodynamic, or structural meaning of the term . In this study, flexibility will be interpreted as the range of motion of all torsion angles of a molecule and thereby the ensemble of all possible torsion states. In other words, we define flexibility as the factor that determines the size and complexity of the conformational space of a molecule (given solvent, temperature, pressure).