An approach to determination of far-field radar cross section (RCS) of electrically large targets from near-field 3-D synthetic aperture radar (SAR) imaging with fixed transmitter is presented. Extrapolations of the transmitted wave and scattered wave are both conducted in a near field to far field transformation. The far-field RCS can be obtained as a function of direction and frequency. As validation, simulations of RCS extraction for squares and a 3-D complex-shaped electric-large flight model are presented.