We have taken UBVRI photoelectric photometry and CORAVEL radial velocities for 6 field RR Lyraes, i.e. SW And, YZ Cap, SW Dra, SS For, RV Phe and V440 Sgr, with the purpose of applying the Baade-Wesselink (B-W) method and determining their absolute magnitudes. The present improvements with respect to previous applications of the method are: a) the use of the (V-I) color, which shows the smallest sensitivity to gravity and metal abundance in the color-visual surface brightness plane. b) the use of a new grid of model atmospheres by Buser and Kurucz (1986), which include an improved treatment of opacity and convection. They provide a complete set of models for the relevant values of effective temperatures, gravities and metal abundances, thus avoiding the need of inaccurate interpolations or extrapolations.