Left: mass fractions of the rocky core (blue) and the gaseous envelope (orange) for all the planets formed in our simulations. The core and the envelope have comparable masses M_core ~ M_env when a planetary mass is ~4 M_⊕. The purple dashed line shows the metal fractions of observed giant planets estimated by Thorngren et al. (2016). The red stars with error bars indicate the metal-mass fractions estimated for Jupiter, Uranus, and Neptune (Fortney & Nettelmann 2010). Right: planetary mass and metallicity for simulated (circles) and observed (crosses) giant planets. The colours indicate the final and observed semi-major axes, respectively. Masses are generally independent of the stellar metallicity.