Polymer powders are used in industrial applications in millions of tons today. Several technologies are established to serve the needs and produce appropriate powders for markets like automotive, electronic, public transport, medicine, textile, and cosmetic, just to name the most important fields. In the case of Additive Manufacturing, Laser Sintering (LS) is based on polymer powders, too. It is well known that powders manufactured “traditionally” match poorly to LS. Typically the powder size distribution (PSD), is not in the preferred range for LS (20 µm to 80 µm). However, even when the PSD fits well, almost all powders fail in LS due to further processing problems. This means that basic information about PSD is by far not enough to qualify powders for LS and predict their processing behaviour. It becomes obvious that beside PSD a further qualification of shape and surface characteristics of particles is mandatory. The presentation describes an approach to qualify single powder particles in a semi-automatic procedure with optical microscopy and a mathematical evaluation. The core value of the calculation is the so-called “elliptic smoothness” (ES). This is the comparison of the contour of a single particle with the contour of a barycentre ellipsis having the same area as the 2D-silhouette of the said particle. ES, as a novel shape factor, gives an impression of the evenness of a particle surface and can be combined with further factors like particle diameter (pd), aspect ratio (ar) and solidity (s) to improve the information about particle shape. Applying this approach on several LS-research and -production powders it becomes clearer how the distributions should look like to be potentially successful in LS-processing.