Atomic gas mass fraction (upper panel) and the molecular-to-atomic mass ratio (lower panel) as a function of stellar mass for the HI-FR and the xCOLDGASS sample. The mean values of the HI-FR and of the different xCOLDGASS samples are indicated as diamonds, with the length of the vertical bar indicating the error of the mean, and the length of the horizontal bar the width of the chosen mass interval. Only galaxies with detections in HI are considered for the mean value of M_HI/M_mol. The yellow line in the upper panel indicates the scaling relation found by Janowiecki et al. (2020) together with the 0.3 dex width adopted by these authors to characterize the HI main sequence.