Next, we screened compositions with greater offequimolar stoichiometry, i.e., all possible permutations of at. fractions x ∈ {0.5, 1.5}, and computed E f,DFT for the min, median, and max predicted energy configurations for each composition (Figure ). With a slope of ∼1 for most compositions, Model 1 predicts relative formation energies of the intra-composition configurations correctly but with a constant error shift that is composition dependent. This yields a lower than desired accuracy with MAE = 41 meV/atom and Pearson correlation coefficient (PCC) = 0.72. To remedy this, E f,DFT was calculated for the 5 elemental X FCC configurations and four random X FCC configurations for each 2-, 3-, and 4-element equimolar compositions, requiring 5 + 4 Synthetic accessibility of a target phase is dependent upon its free energy above the convex hull, E h , subject to standard assumptions for DFT-computed phase stability and thermodynamic synthesizability limits of metastable phases. Êh,M2 is computed from Êf,M2 distributions for select off-equimolar, 5-element composi- tions using Materials Project data 39 and pymatgen 37 (Figure ). Even the minimum E h configurations, let alone a Boltzmann weighted average across configurations, are near or above the typically assumed values for the upper synthesizability limit for metastable materials (∼0.05-0.10 eV/atom above the hull). The strong thermodynamic driving force for decomposition of the FCC phase is qualitatively consistent with the inability of experiments to isolate single-phase FCC solid solutions in this composition space. The hull energy of the phase diagram is lowered significantly by the highly favorable formation of, for example, Mg 2 Sn intermetallic compounds. Therefore, removing Sn and screening Êf,M2 for (Al,Li,Mg,Zn) compositions, the minimum Êh,M2 can be reduced by ∼0.04 eV/atom, which remains high but marginally improves potential for synthesizability from a thermodynamic perspective. In the future, FCC training databases with more elements can be developed to enable accurate predictions of more alloying strategies or altogether different composition spaces that can identify candidate low-density high entropy alloys with low or zero E h .