In this paper, we introduce a linear mathematical model for the Aggregate Production Planning problem for a forestry company operating several sawmills. Considering different types of raw materials, different production parameters, and a group of sawmills, the industry tries to identify the best levels of production, of subcontracting production, and of inventory to satisfy the demand for different product families in order to maximize its revenue. The linear model is solved efficiently with two linear programming software Cplex 8.1 and Xpress-Optimizer 16.10.02, and numerical results indicate the superiority of the latter.