Determination of the spectral type and its uncertainties for all 39 substellar companions in the ExoGRAVITY Spectral Library. The dark gray lines show the sigma difference between the given spectral type and the best fitting spectral type, the latter of which is also highlighted by a vertical light gray line. The spectral type range within 1σ of the best fitting spectral type (area highlighted in gold) is considered the spectral type uncertainty.