  We present a comprehensive investigation of electron capture (EC) ratios
spanning a broad range of atomic numbers. The study employs a self-consistent
computational method that incorporates electron screening, electron
correlations, overlap and exchange corrections, as well as shake-up and
shake-off atomic effects. The electronic wave functions are computed with the
Dirac-Hartree-Fock-Slater (DHFS) method, chosen following a systematic
comparison of binding energies, atomic relaxation energies and Coulomb
amplitudes against other existing methods and experimental data. A novel
feature in the calculations is the use of an energy balance employing atomic
masses, which avoids approximating the electron total binding energy and allows
a more precise determination of the neutrino energy. This leads to a better
agreement of our predictions for capture ratios in comparison with the
experimental ones, especially for low-energy transitions. We expand the
assessment of EC observables uncertainties by incorporating atomic relaxation
energy uncertainties, in contrast to previous studies focusing only on Q-value
and nuclear level energies. Detailed results are presented for nuclei of
practical interest in both nuclear medicine and exotic physics searches
involving liquid Xenon detectors ($^{67}\mathrm{Ga}$, $^{111}\mathrm{In}$,
$^{123}\mathrm{I}$, $^{125}\mathrm{I}$ and $^{125}\mathrm{Xe}$). Our study can
be relevant for astrophysical, nuclear, and medical applications.
