A numerical algorithm is proposed which is suitable to calculate the magnetic field distribution as well as the corresponding nuclear magnetic resonance time signals and frequency spectra induced by susceptibility effects. It accounts for a wide variety of system parameters such as various sample geometries, free and hindered self-diffusion, inhomogeneous susceptibility, and variable spin concentration. It is suitable to cover multiple experimental conditions such as single pulses, echoes, sample spinning at any tilt angle, and field gradient experiments. Typical results are shown that demonstrate the separate and combined influences of self-diffusion and sample spinning on spectral line shapes. Calculated frequency shifts are compared with known analytical expressions and with experimental data on dispersions of magnetic nanoparticles. (C) 2003 American Institute of Physics.