We fitted DFT-D3(BJ) and -D4 damping parameters for all double hybrids except for B2PLYP, B2GP-PLYP and PBE-QIDH-D3(BJ). This included refitting range-separated double hybrids ωB2(GP-)PLYP and RSX-QIDH to explore whether the notably small dispersion corrections for these functionals are impacted by fitting to a larger fit set. The original DFT-D4 fit set consisted of S66x8,[90, 91] S22x5 and NCIBLIND10 which was also adopted for fitting DFT-D3 in 2017 . It has been since argued to use a larger, more diverse fit set. In this vein we use the fit set from ωB97X-3c, with the exclusion of S30L due to limitations to computational resources. The set consists of: ACONF, ADIM6, BSR36,[6, 99, 100] CARBHB12, DARC, HAL59, HEAVY28, IDISP, ORCA 5.0.3 was used for all single-point energy calculations with the def2-QZVP AO basis set. Values for s 6 were determined as detailed in ref. , based on the percentage of CCSD(T)/CBS dispersion energy in noble-gas dimers recovered by the respective DHDF. Then, the three remaining damping parameters, a 1 , s 8 , and a 2 , were optimised by a least-squares fit to (relative) reference energies across all the benchmark sets. Reasonable initial starting parameters of a 1 = 0.4, s 8 = 1 and a 2 = 5 were chosen as in Friede et al. In the instance of fits that resulted in undesirably negative (unphysical) s 8 values, we opted instead for a two parameter fit with s 8 = 0. This is standard practice, where (mostly double hybrids) ] initially optimised negative s 8 values may be indicative of the method overestimating mid-range dispersion. Additionally there was a tendency for a 1 values to optimise to a negative value, which, as recently discussed more in-depth by Friede et al., is also unphysical. Standard statistics for each DFT-D3(BJ) and -D4 corrected DHDHF on each benchmark set are given in Section S2 of the SI and they comprise mean deviations, mean absolute deviations (MADs), root-mean-square deviations, minimum and maximum deviations and deviation ranges. For further detail on the theory behind the dispersion models and fitting procedure we refer the reader to refs. 25, 29 and 30.