Due to its high quantum yield and long fluorescence lifetime, pyrene molecule is a widely used fluorescence probe. From a theoretical-computational viewpoint, the modeling of its emission properties in different environments still represents a challenge, mainly because the coupling with the environment severely affects its emission behavior. We employed our computational-theoretical approach to quantitatively model the pyrene emission, which combines quantum chemical calculations with all-atom molecular dynamics simulations. Our calculated fluorescence properties, well matching the experimental data, highlight that even slight geometrical fluctuations of pyrene at room temperature can provide relevant effects on its radiative lifetime. (C) 2015 Elsevier B.V. All rights reserved.