Gas-to-star fractions, μ_HI (left), μ_H2 (centre), and F_gas = μ_H2/(1 + μ_H2) (right) as functions of M_star compared to z ≃ 0 observational fits (dotted lines) for main-sequence galaxies (Saintonge et al. 2016, 2017; Tacconi et al. 2018). Different dotted lines in the left panel correspond to fixed Log(SFR/M_⊙ yr⁻¹) = 0, –1, –2, –3, –4, and –5, from top to bottom. Dashed magenta lines refer to simulation fits (Appendix F, Table F.2).