Mode I crack opening effects in compression-loaded cracked cylinders were examined using finite element analysis. The situation ahead of the crack tip was characterized using linear elastic fracture mechanics in the form of the stress intensity factor (K) concept. Different cylinder dimensions in combination with different loads and crack radii (circular crack shapes were used) were investigated. By using the line load as normalization parameter for the K values, load independent K-curves (K as a function of the normalized crack length a/W) were obtained. The K-curves were compared for different cylinder dimensions to examine the scaling behavior.