When end milling long fiber reinforced composites, fiber protrusions of the top layers can occur. The lengths of fiber protrusions found on real workpieces with curved contours cannot be explained so far. The lengths of individual fibers to be cut along the tool path depend on tool diameter, local fiber orientation and path geometry. All fibers are separated into two ends at the initial contact with the tool. They define the theoretical maximum lengths of fiber protrusions. A model for these observations has been established. The model is validated by milling experiments using curved contours.