A powder¿s flowability plays a significant role in the quality of products manufactured using laser-based powder bed fusion (PBF-LB/P) (commonly known as Selective Laser Sintering or SLS) [1, 8, 16]. A variety of measurement methods are commonly used for its assessment, with the measurement of the Hausner ratio and the avalanche angle being among the most prevalent. Issues in current measurement practices include the lack of known correlations between the measurement methods and the fact that they do not accurately represent the actual conditions in the PBF process. This study investigates these aspects in connection with the use of flow additives. For the analysis in this study a polyamide 12-based copolymer as the base powder was used. The influence of different flow additives was examined across different concentrations, focusing on their effects on thermal properties, particles¿ geometry and size distribution, as well as flowability according to various measurement methods. The measurements reveal that the impact of the flow additives had no effects on either thermal or geometrical measurement parameters, while a significant enhancement in flowability was achieved for all flow additives. To investigate the influence of pressure and temperature, the application of a rheometer for powder characterization was also attempted, and the encountered challenges were documented. A concluding correlation analysis reveals strong connections between particle parameters (circularity, flow additives, -concentration) and the flowabilities (Hausner ratio and avalanche angle), as well as the results obtained for the flowabilities under the different measurement methods.