Implicit solvation models have been widely used in the literature to study the thermodynamics of the ORR. However, solvation energies computed with various implicit models can differ as much as 0.8 eV. Such energy differences can lead to drastically different conclusions about the reaction thermodynamic landscape. These discrepancies are likely due to variations in implicit solvation parameters, particularly the cavity size, where small differences can result in large solvation energy variations. These significant differences can also be attributed to varying conventions used to calculate thermodynamic properties when solvation is considered. Using the clean surface in vacuum as a reference typically leads to increased stabilization 82 of adsorbates since the solvation energy of the clean surface tends to be negative. In this paper we use the solvated surface convention i.e. the water covered surface is used as a reference (* in Equation ). Numerous studies have employed explicit water techniques to investigate the ORR. Similarly to implicit solvation studies, they often display significant disparities, particularly when different functionals and dispersion corrections are used. 92 Furthermore, using different water orientations, H-down or H-up can lead to inconsistent results. Finally, these disparities can also arise due to a different treatment of the entropy for adsorbed water. Calculations in vacuum and using implicit solvent models often assume that the water reference is taken from a liquid reservoir (H 2 O (l) ) where translation, rotation, and vibration entropy terms are included, and taken from thermodynamic tables. For explicit water studies, instead, this reference is frequently a water molecule removed from the electrode (H 2 O * ), and only vibrational degrees of freedom are used. This latter contribution S vib is typically much smaller (0.06 eV) than the full standard gas entropy S (0.67 eV) which leads to a considerable overestimation of the binding strength for explicit calculations.