Left panel: main sequence of HII galaxies: current SFR derived from the calibration between our SFR averaged over 10 Myr from our SED fitting procedure vs. the LHβ from Eq. (4), as a function of Mass_young (blue points and line) and of Mass_total (red points and line). The green line is from Brinchmann et al. (2004), the cyan line from Chang et al. (2015), and the orange line from Elbaz et al. (2007; see text). Right panel: specific SFR as a function of stellar mass, as in the left panel. In both plots the positions of the genuine starburst 30 Dor in the LMC are given (magenta). The black point in the right panel represents the position of the ULIRG Arp 220 with SFR over ~200 M_⊙yr⁻¹.