A procedure for calculating microscopically the input for standard shell-model calculations, i.e., the core and single-particle energies plus the two-body effective model-space interactions, is presented and applied to nuclei at the start of the sd-shell. Calculations with the JISP16 and Idaho chi EFT (NLO)-L-3 nucleon-nucleon interactions are performed and yield consistent results, which also are similar to phenomenological results in the sd-shell as well as with other theoretical calculations, utilizing other techniques. All results show only a weak A-dependence.