In order to reap the benefits of working in this small-angle regime, one must take into consideration:
* The characteristic length scale of the polymer, e.g. 
* The wavelength of the scattered particles
The ratio  will determine the available angular spectrum of this regime. To see this one may consider the case of elastic scattering (even approximately elastic ).  If the scattering angle is , we may express  as:
so the small-angle condition becomes , determining the relevant angles.