Approximate location of the BLOeM stars in the HRD of BLOeM sample based on spectral-type calibrations described in Sect. 5.4, colour-coded for dwarfs and giants (V–III) and supergiants (II–I) with blue triangles and orange stars, respectively. An estimate of the typical error (subject to calibration error, uncertain reddening, and potential binary contamination) is shown in the bottom left corner. We use the same tracks as plotted in Fig. 2, but include more initial masses (shown in labels). The M_ini = 7.9 M_⊙ track was used to select the BLOeM sample from the Gaia catalogue. Black dots along the track are spaced by 0.05 Myr. Also plotted are the ZAMS and isochrones at 2, 5, 10, 20, and 30 Myr. The labels at the top (split into two rows for clarity) show the spectral types corresponding to the temperature scale for supergiants only (adopted from Table 1). The magnitude cut at G = 16.5 mag and the H-D limit (identified visually) are also marked.