Here, we developed models to compute the Diósi-Penrose collapse time in general atomistic systems (eq. ( )) and homogeneous media (eqs. ( ) and ( )). We applied these models for systems ranging from a small isolated molecule, for which the collapse time is of the order of a billion years, to mesoscopic crystals, whose collapse could occur within days, and macroscopic systems, collapsing within a rontosecond (10 -27 s). We also discuss collapse in the context of decoherence, which is another essential element in the route from quantum to classical, and propose an interferometric experiment to verify the Diósi-Penrose hypothesis.