Notes. The first row shows our definition of a rocky planet orbiting within the empirical habitable zone (eHZ). The second row defines exo-Earth candidates (EECs) as used in the yield estimates for HabEx and LUVOIR. The last columns summarize the occurrence rates for these objects as provided by the assumed exoplanet population. ^(a)Occurrence rates are values for single stars averaged over our input catalog for the given range of spectral types. Because the stellar flux range is spectral type dependent, the number of objects falling within this range, and hence the occurrence rates, varies with spectral type as well. ^(b)The flux range is given by the “recent Venus” and “early Mars” limits and is spectral type dependent (Kopparapu et al. 2014). The values given here correspond to 1 M_⊕ planet orbiting a solar twin. We note that both limits take into account the luminosity evolution of the Sun, which was fainter during the epochs when Venus and Mars provided habitable conditions. For present-day solar luminosity, these insolation limits correspond to separations of 0.75 and 1.77 au, respectively, excluding Venus from, but including Mars in, the eHZ. ^(c)For EECs, the lower limit of the radius range depends on the separation from the star; closer to the star, planets are required to have a larger radius. This can be described by , where S is the insolation. The HabEx and LUVOIR studies focused primarily on solar-type stars and used a corresponding expression based on the semimajor axis, . As we are also interested in M stars, we had to convert this into an expression for S. ^(d) The flux range is given by the “runaway greenhouse” and “maximum greenhouse” limits and is spectral type dependent (Kopparapu et al. 2014). The values given here correspond to a 1 M_⊕ planet orbiting a solar twin.