Comparison of the 1D surface density evolution as a function of disc radius for a planet-less disc of M_d = 0.07 M_⊙, using L_X = 1 × 10³⁰ erg s⁻¹ for the photoevaporation profiles by O12 and P19. The different lines are drawn at [0, 25, 50, 60, 70, 72, 75, 80, 85, 90, 95, 99]% of the corresponding total disc lifetime t_disc. The dotted line shows the approximate location of gap opening due to photoevaporation for each model.