An investigation has been carried out of the packing densities of alumina and silicon carbide powders to determine the effect of material properties, particle shape and size distribution when subjected to tapping. The variations of packing density with tapping number for various powders are experimentally measured. It is shown that the measured relationship between packing density and tapping number can satisfactorily be described by either the modified Heckel or Kawakita equation. An attempt is then made to correlate the parameters in the two equations with the Hausner ratio. The results suggest that the packing of fine powders subjected to tapping can be characterised by this ratio.