Density of the ultra-hot Jupiters with known masses as a function of their equilibrium temperatures (T_eq > 2000 K). The colour bar shows the ratio of the exoplanet atmosphere annulus surface and the stellar disc area (TS), considering one scale height (H). The TS is shown normalised for the sample of exoplanets shown: the TS expands from 0 (lowest transmission) to 1 (highest transmission). The size of the markers is indicative of the H of each exoplanet. Very high-density ultra-hot Jupiters (>4ρ_Jup) such as WASP-18b and KELT-9b (with temperature >3000 K) have been discarded for a better visualisation of the sample. The values are calculated with the information extracted from the Transiting Extrasolar Planets catalogue (TEPCat; Southworth 2011).