This paper presents a new capacity planning framework integrating internal production processes and external demand supply chains. Since planning is concerned with preparing how resources are arranged before future situations are realized, the planning problem should consider the entire aspect of a company, including internal and external aspects. Most previous works focused on only one aspect by simplifying the other. The proposed framework is formulated as a mixed integer programming (MILP) problem with an aim to establishing a rigorous decision-making tool. Lessons learned during their industrial implementations are discussed with some remarks.