The cotton harvesting industry is in the beginnings of its next technological advance, cotton harvesters that form cotton modules inside the machine then deposit them off the rows. These new machines eliminate the need for extra labor and equipment, but are more expensive than conventional pickers. Increased field efficiency is also a benefit of the on-board module builders. The problem facing producers is determining the optimal number of acres to plan for harvest when trying to decide which harvester to purchase. This paper examines two objectives. First, determine the cost per acre of both conventional and on-board module harvester systems for different acreage levels assuming harvest hours per year are fixed. Second, make the harvest hours per season stochastic to determine the cost per acre under different farm sizes for each type of cotton picker. The results show that the maximum benefits of the new machines are realized with larger farms when a larger number of acres need to be harvested in the harvest period. Results should help farmers plan both their cotton acre estimates as well as their purchase decisions for new cotton pickers.