Mass–radius isochrone for substellar objects and VLMSs at an age of 5 Gyr (Baraffe et al. 2003, black dots). Jupiter’s and Saturn’s positions are indicated with crosses. Horizontal lines indicate the range of possible radii for Kepler-1625 b estimated from the Teachey et al. (2018) transit lightcurves and from the uncertainties in the stellar radius. Theblue bars at the bottom refer to the mass estimates that are compatible with the isochrone (lower intervals) and as derived from the dynamical signatures in the transits (upper interval).