Effect of the atmospheric model on the evolution of Jupiter and Saturn. We compare the atmospheric models of Fortney et al. (2011) and Marley et al. (1999). The calculations use the SR2018 phase diagram with T_offset = 350 K (Sect. 3.1). Top panel: present-day helium mass fraction as a function of pressure. The black dot shows the Galileo measured value. Bottom panel: effective temperature as a function of age. The black dashed lines correspond to homogeneous evolution calculations while the black dots show the measured effective temperature and the errorbar gives the uncertainty in terms of age.