The shear testing protocol developed by Jenike in 1964 is commonly used to characterize powder flow in the food and pharmaceutical industries. The protocol requires the measurement of consolidated bulk density and the stress required to shear a powder bed under a series of normal consolidation stresses. In this work, the influence of preconsolidation stress and surface-volume mean particle diameter on the bulk density of 13 milled lactose powders consolidated in an annular shear cell below 5 kPa is examined. Five empirical correlations that relate bulk density to preconsolidation stress are tested. Each correlation contains two fitting parameters and their values are determined by regression; the parameters are further correlated with particle diameter. A new correlation that simultaneously relates bulk density to preconsolidation stress and particle diameter is proposed. The correlation is valid for milled lactose powders of similar to 29-223 mu m and preconsolidated at 0.31-4.85 kPa, and can estimate bulk density to +/- 10% of the measured bulk density. It is a convenient tool for the estimation of the bulk density term in an earlier correlation that links the cohesion of milled lactose powders to particle surface area per unit volume and preconsolidation stress. (c) 2014 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.