Maximum luminosity for a given total mass and surface X_H. Left: Maximum luminosity plotted against surface X_H for total masses ranging from 1 M_⊙ to 18 M_⊙. Right: Maximum luminosity plotted against total mass for X_H values ranging from 0 to 0.7. The plus signs indicate maximum luminosities achievable from partially stripped structure models, while the dashed black lines represent our best-fit relations from Eq. 2. The green dashed line in the right sub-panel corresponds to the MLR for pure-He models. Stripped star luminosities and spectroscopic masses from Götberg et al. (2023) and Ramachandran et al. (2023, 2024) are over-plotted.