From top to bottom: clumping factor ratio / (left) and / (right) for the OB supergiants, dwarfs, and giants derived in this work, as a function of the invariant log Q′ = log (Ṁ_max/R_*^1.5), in units of M_⊙ yr⁻¹ R_⊙⁻¹. Symbols and colours as in Fig. 4, except for empty symbols, which indicate sources with upper limits for Ṁ_max. Dotted-dashed lines correspond to sources with two solutions for either Ṁ_max or clumping factors at the outermost wind regions.