Filling factor ϕ as a function of size s for different distances to the star r for silicate grains composed of 0.2 µm monomers in our standard disc model with growth and fragmentation. Left: without compaction. Right: with compaction. The inset is a zoom of the light grey box showing only tracks for R₀ = 10 and 100 au. The dash-dotted lines show the impact of multiplying υstick from Eq. (14) by 100.