Fiducial stellar mass versus Euclid (+ancillary) photometry-derived stellar mass for true z > 6 galaxies (upper panels) and z > 6 contaminants (lower panels), for three scenarios of Euclid and ancillary photometry. The number of galaxies shown is indicated in the upper-left corner of each panel, as is the bias and scatter σ_f. The bias is defined as mean[(M_sim − M_fid)/M_fid] and the scatter as rms[(M_sim − M_fid)/M_fid]. The colour intensity corresponds to the number of galaxies in each bin (darker colours correspond to more sources).