CO-to-H₂ conversion factor (α_CO) vs. metallicity, adapted from Bolatto et al. (2013) to include the main properties of the CO clouds in Leo T detected in this work. The α_CO estimations (red, green and unfilled-red inverted triangles) correspond to upper limits (see Sect. 3), with uncertainties of the order of ∼24-33%. The figure includes a recompilation of CO structures reported in different galaxy samples: WLM (Rubio et al. 2015); DDO 70 (Shi et al. 2020); DDO 50 and DDO 53 (Shi et al. 2016); local LIRGs and ULIRGs (Leroy et al. 2011); LMC and other magellanic irregular galaxies (Israel 1997); and other local group galaxies (Madden et al. 1997; Gratier et al. 2010; Smith et al. 2012). The figure also contains theoretical models of α_CO(Z) from Israel (1997) (yellow line), Narayanan et al. (2012) (green line), Feldmann et al. (2012) (blue line), and Glover & Mac Low (2011) (red line). The light blue and brown areas correspond to the α_CO ranges for the MW and ULIRGs recommended by Bolatto et al. (2013).