In this paper, we present our first results on the mobility coefficients in the systems of magnetic dipolar particles. In our study, we investigate the influence of chain formation and polydispersity of particles on self-diffusion. The work is purely theoretical and combines direct calculations with the density functional approach to calculate equilibrium densities of chains. We study mainly bulk systems. It is shown that the formation of chains leads to the average decrease of mobility in monodisperse systems, but in the case of bidisperse particle size distribution, the particle mobility becomes a function of the fractional composition. The mobility coefficients obtained here are important for calculating the diffusion coefficients in case of gradient-induced diffusion (be that of the field or density gradient) in magnetic fluids with chain aggregates
