Production planning and scheduling are significant activities for companies that follow an engineer-to-order (ETO) production. A hierarchical production planning (HPP) framework has been proposed to generate long-term, medium-term, and short-term production plans using a common granularity of production equipment and unit time for ETO production of large products. This research proposes the medium-term production planning method based on an integer programming (IP) formulation to create a weekly production plan according to the results of the long-term production plan. The proposed medium-term production planning method simultaneously determines the monthly time spans to carry out each operation and the production schedule of the operations to be carried out in each monthly time span. The production scheduling determines the start and finish dates and times for each operation of each part in the individual monthly time spans. The start and finish weeks for each operation of each part are obtained from the scheduling results to use as a weekly load plan for the medium-term production plan. The proposed medium-term production planning method can improve the flexibility of the HPP. Case studies have been carried out to generate long-term and medium-term production plans by using production conditions that consider the practical ETO production for large products.