Each panel shows a two-dimensional histogram comparing one prediction of the magnetic field strength to the simulated, mass-averaged value. These distributions include all pixels across all R8 snapshots. The left panel estimates the magnetic field using Equation (24), where the total CR energy density e_c is assumed to be a spatially constant value determined by equipartition with the spatial average value of the magnetic energy density. The middle panel also assumes spatially constant e_c, adopting a calibrated relationship between cosmic-ray pressure and star formation rate (SFR) per unit area, Σ_SFR. The right panel assumes a spatially constant e_c and estimates the mean CR pressure as a fraction of the total dynamical equilibrium pressure (or ISM weight; Equation (37)). In all three panels, the black, dashed line shows B_pred = B_avg, and the purple line shows the best-fit power law to the distribution. The red points represent the box-averaged values of B_pred and B_avg from each simulation snapshot. In all three models, we see an improvement in the scaling of B_pred relative to B_avg compared to the distribution shown in Figure 3.