While there are many affordable quantum chemistry methods that can be used to calculate thermochemistry for large molecules, this work focuses on a subset of popular methods that span different levels of theory. In particular, as summarized in Table , we consider the GGA functional BP86 , the meta-GGA functional TPSS , the hybrid functionals B3LYP-D3 56 , B97D3 57 , M06-2X 58 , PBE0 59 , ωB97X-D 60 and ωB97M-V 61 , the double hybrid functionals B2PLYPD and CAM-B3LYP , the composite methods CBS-QB3 64 and G4 . Additionally, the domain-based local pairwise natural orbital (DLPNO) coupled clus-ter methods are considered, specifically DLPNO-CCSD(T) and DLPNO-CCSD(T)-F12. These methods are an approximation on traditional coupled cluster calculations that allow for a near-linear scaling in the coupled cluster iterations with minimal loss of accuracy.