a Singapore-MIT Alliance , SMA-NTU Office, N2-B2C-15, Nanyang Technological University (NTU) , Abstract. Available-to-promise (ATP) is a quantity that can be used to determine whether a firm can fill customer orders by the requested date. This paper describes a Web-based flexible ATP computation system (WebATP) which provides enhanced flexibility during ATP computation. A dynamic bill-of-material (BOM) is used to simplify the BOM exploding process which makes ATP computation less expensive. Case study shows that WebATP can help firms to understand their capability for filling customer demands better. Being Web enabled, WebATP can be accessed from any geographical locations and from any computer platform. It can also be used as a 'what-if ' scenario planning tool.Authors: M. H. Xiong, Singapore-MIT Alliance, SMA-NTU Office, N2-B2C-15, Nanyang Technological University (NTU),