Metal additive manufacturing processes are increasingly used to produce high-performance engineering parts. However, defects such as porosity remain a major challenge, negatively affecting mechanical performance. Therefore, damage tolerant approaches have been adopted, which accounts for the inherent internal defects in the design stage. This approach requires the information about porosity distribution within the material, which can be experimentally evaluated using X-ray micro computed tomography (CT). Accordingly, the finite element analysis can be carried out accounting for the material porosity, previously converted into an effective void volume fraction [1]. The present study aims to assess the accuracy of the mapping procedure used to transfer the porosity from the micro-CT images to the finite element mesh used in the numerical analysis. The uniaxial tensile specimen of stainless steel 316L obtained by material extrusion was selected to evaluate the mapping procedure. The first step comprises the 3D representation of the specimen using a mesh composed by tetrahedral finite elements, where the internal porosity is defined in each element by the void volume fraction. The second step is the mapping of the porosity from this mesh to the mesh used in the numerical analysis, which is composed by hexahedral finite elements. The impact of the mesh size on the obtained porosity level was studied, considering different meshes in both steps, namely element size ranging between 0.019 and 0.5 mm in the tetrahedral mesh and element size ranging between 0.1 and 0.5 mm in the hexahedral mesh. The results highlight the correlation between mesh size and volume fraction of porosity assigned locally.