Viscosity data for near-monodisperse spherical particles taken from the literature are compared in terms of the maximum density for flow derived from them using the Krieger-Dougherty equation. The data indicate a dependence of maximum density on particle size in both the low and high shear limit. At each limit there appears to be a decrease in maximum volume fraction with increasing particle size of approximately 0.1, with the transition centered upon a particle diameter of order 400 nm.