Abstract The flocculation degree of a dense slurry was evaluated by hydrostatic pressure measurement. In order to discuss the relationship between the results obtained from the hydrostatic pressure measurement and the final packing fraction of a sediment, the ratio of apparent weight flux of the depositing particle to that of the settling particle, U b/ U u was introduced. It was shown that the final packing fraction of the sediment increased with U b/ U u. In addition, the value of U b/ U u was theoretically estimated when the particles were well dispersed and hindered settling occurred, and the estimated value was compared with the experimental value in order to discuss the settling behavior in detail.