Density as a function of temperature for Neptune (top) and Uranus (bottom). The profiles were calculated using our fiducial model (REOS for water and SESAME Dry Sand for rock; solid black lines) and two alternative test models: one substituting the water EOS with SESAME (dashed blue lines) and another substituting the rock EOS with QEOS for SiO₂ (dotted yellow lines). To isolate the effect of the EOS, the profiles for each planet were computed using identical interior parameters drawn from a representative posterior solution. The SESAME water EOS yields denser profiles than the fiducial REOS throughout most of the interior. Similarly, using QEOS for SiO₂ instead of SESAME Dry Sand results in denser structural profiles, with the differences being most prominent in Uranus.