The defects present in an additively manufactured component deteriorate its mechanical, especially fatigue performance. During loading, these defects influence the stress concentration, promote the fatigue crack initiation and thus, lead to a lower fatigue performance. In this study, the effect of defect shape and size on the Mode-I stress intensity factor (KI) of the short cracks initiating from both 2D and 3D internal defects was investigated using linear elastic finite element analysis (FEA). The shape of the defect was varied by altering the aspect ratio (width/height) from 0 to 1. Later, the dimensionless results from FEA were utilized to calculate the SIF in defects with half-span width of range 10-100 µm. As a result, the influence of defect shape on the SIF was only observed in the short crack length regimes and the measure of SIF was observed to increase with decreasing aspect ratio for a given crack length.