A segmented model for the vertical distribution of cross-sectional ring area was built with data from 32 Atlas cedars sampled in the south of France. The trees, with contrasted social status, were chosen within eight stands as different as possible in age, site index, and density. The first segmentation point of the model indicates the base of the efficient crown (i.e. really contributing to the bole thickness increment) and the second one the upper limit of the butt swell. Statistical relations were established to predict the parameters of the individual model from standard whole-tree characteristics. The overall final model predicts the cross-sectional area of the ring from girth and basal area increment at breast height, total height, and height to the base of the full live crown. This relation is useful to predict the evolution of stem profile and the tree volume increment. It can be easily incorporated into an individual tree growth and yield model.