Strip width necking may be quite significant on cold rolling mills. Tocompensate for this unpredicted phenomenon, hot strips are oftenordered with an over-width with resulting substantial over costs, fortrimming in particular. Based upon numerical simulation supportedby rolling trials, the main factors that effect strip width variation havebeen quantified: edge drop, transverse stress relaxation, thermalcontraction. Potential width actuators to be implemented on industrialcold rolling lines have been identified.