Transit depth of all hypothetical Earth-like planets around their M-host stars for a fixed resolving power of 100 (coloured lines). The error bars show two sigma (standard deviation), single transit errors for selected spectral features, and selected M-dwarf planets at 10 parsecs with optimised wavelength bins. In black: calculated using high resolution JWST NIRSpec BOTS disperser and filter. In grey: calculated using NIRCam weak lens filters and high resolution NIRCam grism filters. Central wavelengths and bandwidths are calculated individually to distinguish between spectral absorption features (see Sect. 3.4.2).