DHH is the electron density peak-peak distance between bilayer leaflets in a scattering experiment, along the surface normal going through the bilayer. The peaks are usually located close to the phosphate regions, due to the high density of electrons of the phosphorus and oxygen atoms . The average distance between phosphate beads (PO4-PO4) is often used when comparing the bilayer thickness of CG simulations to experimentally determined DHH . However, the DHH and PO4-PO4 distances are in general not equal because phospholipid headgroups are dynamic and the headgroup is often located at the same plane as the phosphate region, which slightly changes the location of the electron peak . Instead, we calculate the DHH directly from the CG simulation by assigning the appropriate number of electrons to each CG bead and calculating the peak-peak distance from the resulting electron density (using gmx density in GROMACS). We find this protocol leads to better agreement with DHH values obtained from SDP modeling compared to using the PO4-PO4 distances. The electron density was smoothened using a convolution window of 5 ns (5 frames).