Radius (top) and density (bottom) as a function of mass for transiting brown dwarfs and giant planets (0.5–13 M_Jup) with percentage errors <10% for both mass and radius in the NASA Exoplanet Archive³. Transiting brown dwarfs – of which there are a total of 16 with well-defined masses and radii – are from the literature summary found in Mireles et al. (2020). The stars denote NGTS-13b, and the vertical dashed lines mark masses of 4 M_Jup and 13 M_Jup (the latter being the approximate lower mass limit for brown dwarfs). The colors of the symbols correspond to equilibrium temperatures in the top plot and host star masses in the bottom plot. The downward trend in maximum radii with increasing mass exhibits the effect of stronger surface gravity on more massive objects, which is clearly displayed by the linear trend in density. In the top plot, we only display planets that also have an equilibrium temperature in the archive: a total of 133 previously known planets, including 14 with masses greater than 4 M_Jup.