[C II] LF derived with SPRITZ assuming different relations (see Sect. 3.1). We compare the results with [C II] observations in the Local Universe by Hemmati et al. (2017), at z ∼ 4.45 by Yan et al. (2020) and Loiacono et al. (2021), at z ∼ 5.5 by Capak et al. (2015), at z ∼ 6.3 by Yamaguchi et al. (2017), and at z ∼ 6.9 by Decarli et al. (2020). We also report the model predictions of Popping et al. (2016, dashed magenta lines) and Lagache et al. (2018, dotted red lines) at z ≥ 4.7. The shaded areas (same colours as the solid lines) show the uncertainties of the considered [C II] relations and the 1σ errors on the SPRITZ input LFs and GSMFs.