A micromagnetic model for simulation of magnetic force microscope (MFM) tips is described. It incorporates a mesh of general polyhedra to allow magnetic films of arbitrary overall shape to be considered. A hierarchical method is employed for rapid evaluation of demagnetizing fields. Results for permalloy coatings of pyramidal tips are presented which show that the precise configuration of the magnetic film can produce differing magnetic behavior in comparison with experiment. (C) 1997 American Institute of Physics.