The method is based on analysing the intensity of excess light scattering in dilute solutions (in relation to the scattering in pure solvent) depending on the angle. The dimensions of macromolecules and molecular complexes are usually tens of nanometres, much smaller than the light wavelength. In that case, the intensity enables the calculation of the molecular weight of macromolecules at a certain fixed angle, considering them as point-scatterers (need to know their concentration). Based on the scattered light intensity versus the scattering angle, the rms radius of gyration can be calculated for macromolecules in a solution, taking into account the destructive interference of light that is scattered by various monomeric units.