A liquid of superconducting vortices generates a transverse thermoelectric response. This Nernst signal has a tail deep in the normal state due to superconducting ﬂuctuations. Here, we present a study of the Nernst eﬀect in two-dimensional hetero-structures of Nb-doped strontium titanate (STO) and in amorphous MoGe. The Nernst signal generated by ephemeral Cooper pairs above the critical temperature has the magnitude expected by theory in STO. On the other hand, the peak amplitude of the vortex Nernst signal below Tc is comparable in both and in numerous other superconductors despite the large distribution of the critical temperature and the critical magnetic ﬁelds. In four superconductors belonging to diﬀerent families, the maximum Nernst signal corresponds to an entropy per vortex per layer of ≈ kBln2.