Spin-echo small-angle neutron scattering (SESANS) is an efficient method to measure particle sizes in real space because it eliminates the need for strong collimation of the beam. In this paper we show calculations on the gain in intensity one achieves for measuring the radius of gyration with SESANS compared to conventional SANS. The gain in intensity is greatest for long length scales. This gain is orders of magnitude for particles larger than 100 nm .