The present study investigated the effects of set radius of curvature and fiber bundle size on the precision of the radius of curvature during continuous carbon fiber three-dimensional (3D) printing. First, individual circles with various radii using various sizes of fiber bundles were printed with a 3D printer. It was demonstrated that with a larger fiber bundle size or a smaller set radius, the printed radius would be lower than the set value. Based on the printing experiments, twist and path length difference models were constructed to predict the actual printed radius. Comparison between the models and experimental values verified that the twist model provides the upper bound on the printed radius and the path length difference model provides the lower bound.