Dust density as a function of height for grains of five representative grain sizes within a disc with the BOD, α = 10⁻⁴ and Σ_g,0 = 1000 g cm⁻², at 3 AU. The black line shows the gas density of the disc. The dashed gray line shows the dust-to-gas ratio as a function of height for the whole grain size distribution. The dust-to-gas ratio of the smallest particles of the sample remains constant, but as grains get larger they get more affected by settling. Consequently, the largest grain (1 cm) is mostly concentrated at the midplane.