Relation between the metallicity, [M/H]_tot, and the strength of dust depletion, [Zn/Fe]_fit, in the neutral ISM in the Milky Way, LMC, SMC, and DLAs. The solid line shows a linear fit to the data, including uncertainties on both axes, [Zn/Fe]_fit = 1.08 + 0.57 × [M/H]_tot, with uncertainties of 0.03 and 0.04 for the intercept and slope, respectively. The dotted lines mark the region within the resulting 0.26 internal scatter of the relation. The Milky Way data are from De Cia et al. (2021). The DLA data are from (De Cia et al. 2018), and they show the observed [Zn/Fe].