Simulations of vesicles and even whole-cell-scale systems have previously been investigated using the Martini force field . The underlying biophysics of bilayer bending is therefore important to model and reproduce. We therefore estimated bilayer bending moduli (kc) for a selection of lipids that have previously been studied by Doktorova et al. using atomistic CHARMM36 simulations . Figure ,A shows the correlation between kc values obtained from lipid tail splay using the Real-Space Fluctuations (RSF) method , comparing bilayer simulations using Martini 2, Martini 3, and CHARMM36. The RSF results obtained using the reparametrized Martini 3 lipids show an improved correlation with CHARMM36 data compared to Martini 2. We also observe a general improvement in average P2 bond order parameters compared to atomistic results (Figure ,B), in agreement with the improved lipid tail splay quantified by the RSF method. APL values also show a better correlation with atomistic data compared to Martini 2, although they are systematically lower (SI Figure ), as previously discussed.