Equilibrium temperature of known ultra-hot Jupiters (T_eq > 2000 K) with measured mass calculated assuming zero albedo, represented as a function of the planet density. The colour bar shows the ratio of the exoplanet atmosphere annulus surface to the stellar disc area (TS) normalised to this particular sample, so the planet with the largest transmission has a value equal to unity. We assumed a mean molecular weight μ = 2.3 when computing the planet scale height, H. The symbol size of the markers is proportional to H of each planet. All these values were calculated with the information extracted from the TEPCat catalogue (Southworth 2011).