In mass customization, the focus is variety and customization through flexibility and quick responsiveness. Mass customizers seek to provide personalized, custom-designed products at low prices to give customers exactly what they want and to provide sufficient variety in products and services. The idea of the product family is the most adequate approach to realize mass customization. An understanding of customer needs using functional decomposition becomes necessary to enhance the performance of the product family. This paper focuses on functional architecture modeling based on customer need regarding sub-functions for the product family. A quantitative functional model captures product functionality and customer need. Based on customer need ratings and sub-function, a product-function matrix was created. Additionally, a product-product matrix was generated to provide a similarity index among product families. A case study for implementing the functional architecture modeling was performed on the single use cameras.