Several different optical sensors were investigated to detect sugarcane yield on a billet type sugarcane harvester. These sensors included an over-head optical sensor and a below-the-conveyor sensor. Both sensors indicated mass flow rate from a volume measurement of the cane on the conveyor slats. Both systems gave good results with linear line calibration equations and adjusted R-square values from 0.96 to 0.97. Weight wagon weights in the 0.6 to 1.6 metric ton range were estimated to 7.5% on average and decreased as larger weights were totaled. Statistical analysis indicated cane variety, speed of combine, cutting distance, and lay of cane were not significant to weight wagon weight prediction.