In recent years, laser powder bed fusion (L-PBF) has become an interesting method for producing metal components with complex shapes. However, L-PBF can lead to defects like porosity, affecting the quality and reliability of the final components. This study investigates the structural defects and relative density of AISI 316L stainless steel with 2.5 wt.% Cu fabricated via L-PBF under varying processing parameters. The relative density of the samples was evaluated using a combination of optical microscopy (OM), Archimedes density method, and x-ray computed tomography (XCT), allowing for a comprehensive analysis of defect morphology, including pore size, shape, and distribution. The primary objective of this research is to compare the accuracy and effectiveness of these three density measurement methods, which have not been widely compared for this specific alloy. The results show differences between the methods, with XCT providing a 3D perspective of porosity, OM providing detailed 2D surface analysis, and the Archimedes method being sensitive to surface defects and cracks. These findings highlight the importance of selecting appropriate measurement techniques for evaluating the quality of additive manufacturing parts and highlight the influence of processing parameters on defect formation and density.