Zero point and slope of the different SBCRs determined using the different PR relations in Table 1. We show the calibrated and theoretical (PARSEC) SBCRs for solar and metal poor Cepheids determined by Bailleul et al. (2025) (black). The turquoise points indicate the slope and zero point of the SBCRs (MW, LMC, and SMC) using the PR relation calibrated in this paper. In the centre of each dashed rectangle, the mean value is indicated with a black cross. The height (width) of the rectangle is three times the standard deviation (3σ) of the zero points found using the various PR relations. Relations without an uncertainty in Table 1 are shown without uncertainty in this figure.