An experimental study of the packing of a coal heap has been carried out. The overall bulk density of a coal heap is considered as a function of a number of variables, viz. flow rate, conveyor belt speed, the height of the disengagement point of the conveyor belt, coal particle density, moisture content, the size of the heap and coal particle size distribution. The effects of the dimensionless numbers resulting from dimensional analysis on the overall packing density of a coal heap have been experimentally examined and analysed. The results are considered to be useful in developing an empirical method for the estimation of the packing density of a large stockpile in practice.