Abstract Barium hexaferrites have been widely used as permanent magnets, however one of the most important parameters that characterizes these ferrites is the switching field distribution (SFD). This work calculates the SFD on a small particle barium ferrite (BaFe 12 O 19 ) obtained by coprecipitation from chlorides in an alkaline medium using the irreversible component of the magnetization. Forward and reverse switching field distribution curves were obtained by differentiation of isothermal remanent magnetization (IRM) and dc demagnetisation (DCD) curves. It was found that both values differ by a factor of 3.5, quite away from the value of non-interacting systems. The Henkel plot was built from these data sets, indicating a predominant region with demagnetising interaction between particles, and a small region in which the particles interact constructively to the magnetization, according to the Preisach model framework.