The interactions between charged colloidal particles in an electrolyte may be described by usual Debye-Huckel theory provided the source of the electric field is suitably renormalized. For spherical colloids, we reconsider and simplify the treatment of the popular proposal put forward by Alexander et al. (J. Chem. Phys. 1984, 80, 5776), which has proven efficient in predicting renormalized quantities (charge and salt content). We give explicit formulas for the effective charge and describe the most efficient way to apply the renormalization prescription of Alexander et al. in practice. Particular attention is paid to the definition of the relevant screening length, an issue that appears to be confused in the literature.