Normalised Hα luminosities as a function of spectral type for the M dwarfs contained in the Carmencita catalogue (upper left), CARMENES GTO target sample (upper right), 14 pc sample (lower left) and 7 pc sample (lower right). The red line indicates the values of Hα emission that our observations are sensitive to as a function of spectral type, which is defined as pEW (Hα) = −0.5Å. Stars with values greater than this are considered to be Hα inactive stars. The values below the minimum detectable emission, or Hα inactive stars, are not shown on the plot, but instead the total number of Hα inactive stars is shown. Also indicated is a population of extremely Hα active stars that are defined as having pEW(Hα) < −8.0Å, which are only visible at later spectral types (solid blue line).