This paper reports the study of a multiple horizontal diamagnetically stabilized levitation setup with two or more free floating permanent magnets. In a first step, the authors present the development of a fast and accurate analytical calculation method for the equilibrium point determination and stability check of the floating magnets. The proposed method uses equivalent magnetic charges for modeling the permanent magnets yielding compact analytical formulas for the flux density. Furthermore, demagnetization in open-loop of the used NdFeB magnets is analytically taken into account by determining their operating point on the BH curve. Compared to sole numerical approaches, the developed calculation method offers a significant reduction of computation time and is especially suitable when performing parameter variations. Finally, the calculation results are validated against several experimental levitation setups including one to three floating magnets.