Left panel: comparison between J-PLUS and spectroscopic Hα emission line fluxes. The errorbars represent the J-PLUS uncertainties and the shaded areas the spectroscopic ones. The ratio between the fluxes is shown in the lower panel, with the median ratios of CALIFA, SDSS and the total sample represented in orange, blue and black dashed lines, respectively. Right panel: normalized distribution of the flux ratios with a Gaussian curve fitted. The median comparison ratio ℛ and its dispersion are displayed in the panel.