Domain state energy calculations have been made for submicron magnetite cubes, based on a model consisting of planar domains of uniform magnetization separated by 180¿ domain walls (DWs). The magnetization within a DW is assumed to rotate uniformly, resulting in the appearance of magnetic poles of average density ¿(2/&pgr;)Js on the particle faces bounding the DWs. Equilibrium domain structure configurations have been determined by minimization of the sum of the demagnetizing and wall energies. Domain structure transition sizes and particle remanences are reported for two-domain and three-domain magnetite cubes.