Average stellar (coloured solid) and gas (coloured dashed) metallicity as a function of stellar mass for different redshifts in NEWHORIZON as indicated in the panel. The error bars stand for the error around the mean. Observational fits for the stellar metallicity from Gallazzi et al. (2014; solid black at z = 0.1, and dashed black at z = 0.7) and from Panter et al. (2008; solid grey) are also shown. The metallicity of both the gas and stellar component are decreasing with increasing redshift owing to less chemically enriched galaxies.