A method for the calculation of equilibrium sedimentation profiles of charged colloids, in the presence of added salt, is presented. It is found that the concentration of the colloidal particles obeys a nonlinear equation, which can be solved by a numerical method. The assumptions used are as follows : each species is subjected to balanced forces; the electrical neutrality condition is verified locally; the colloid particles have a constant charge; they are spherical and their size is much smaller than the gravitational length; the main departure from ideality arises from the hard-sphere contribution, and it may be derived from the Carnahan-Starling equation of state. The results are compared with recent experimental data. It is found that the agreement is excellent in the case of high screening (excess of salt). When the salt concentration is decreased, large discrepancies are observed. The salt-free case is also treated. In each case, tentative interpretations are examined.