Layered hybrid organic perovskites (HOPs) structures are a class of low-cost two-dimensional materials that exhibit out- standing optical properties, related to dielectric and quantum confinement effects. Whereas modeling and understanding of quantum confinement are well developed for conventional semiconductors, such knowledge is still lacking for 2D HOPs. In this work, concepts of effective mass and quantum well are carefully investigated and their applicability to 2D HOPs is dis- cussed. For ultrathin layers, the effective-mass model fails. Ab- sence of superlattice coupling and importance of non-parabo- licity effects prevents the use of simple empirical models based on effective masses and envelope function approxima- tions. An alternative method is suggested in which 2D HOPs are treated as composite materials, and a first-principles ap- proach to the calculation of band offsets is introduced. These findings might also be relevant for other classes of layered 2D functional materials.