<p>Additive manufacturing (AM) offers significantly greater design freedom while minimizing tooling costs, which makes it an advanced alternative to traditional manufacturing methods. Although various design guidelines and optimization techniques for AM have been developed, there is still a lack of objective and efficient metrics for quantitatively evaluating the manufacturability of parts across different AM processes. To address this gap, this study proposes the additive manufacturability Index (AMI), a comprehensive metric designed to quantitatively assess the geometric suitability of part designs across various AM processes. The AMI integrates multiple critical factors like material efficiency, volume of support structures, and geometric features that influence warping, toppling, and surface roughness. To validate the effectiveness of the proposed metric, we examined a wide range of AM part designs, from simple geometrical shapes to complex internal lattice structures and industrial components. In addition, experimental validations were performed with four geometries printed using a material extrusion process where each geometry represented the specific challenges faced during printing. The results demonstrated that the AMI reliably identifies favorable designs and determines optimal build orientations for specific AM technologies. The experiments validated the occurrence of defects such as warping, toppling, and surface roughness, and the corresponding AMIs provided a quantitative measure of the parts’ additive manufacturability. Ultimately, this study provides a systematic tool for designers to enhance manufacturing processes, improve material efficiency, and ensure part quality in the early stages of product development.</p> Graphical Abstract