Single-domain, high-remanence particles are the prerequisite for their application in magnetic high-density recording systems. Analytical calculations for the transition between single and multidomain configurations remain unprecise because the calculation of the stray field requires strong simplifications. By means of the three-dimensional finite element method, zero-field magnetization structures of magnetically hard and soft thin film elements and cubic particles have been determined. Numerical results are compared with analytical calculations showing that the latter results depend sensitively on the energy determined for vortex structures.