Sum of neutrino masses ∑m_ν in the inverted ordering (red solid line) scenarios and in the normal ordering (blue solid line), including the uncertainties on the mass squared differences from oscillation experiments, as a function of the lightest neutrino mass. The grey dot-dashed lines show the 95% CL upper bounds from Planck only (dark grey), and in combination with external data (Planck +ext., light grey). For the latter we use the value quoted in Alam et al. (2021) for Planck +Pantheon-SNe+SDSS(BAO+RSD)+DES 3 × 2pt, which includes Planck, Pantheon type Ia supernovae, baryon acoustic oscillations and redshift-space distortions from the Sloan Digital Sky Survey, and weak lensing measurements from the Dark Energy Survey. The region above the blue dashed line is excluded at 95% CL by Euclid only primary probes. The orange shading shows the 68% and 95% CL limits on ∑m_ν from Euclid +Planck in the baseline ΛCDM+∑m_ν model, assuming a fiducial value ∑m_ν = 60 meV. The 68% and 95% CL constraints from Euclid +CMB-S4+LiteBIRD are shown in green. We note that we split the two constraints into two different ranges of the lightest neutrino mass only to avoid an overlap of the two shadings. Assuming that the true value of the neutrino mass sum is indeed the minimum allowed by neutrino oscillation experiments in normal ordering, the combination Euclid +CMB-S4+LiteBIRD will rule out the inverted ordering at 2.5 σ.