In this research fuzzy logic approach is applied to solve the problem of inventory lot-sizing under uncertain demand and supply. Conventional stochastic inventory lot-sizing model and existing dynamic models determine only uncertain demand. However, unavailability of supply can happen in many types of manufacturing system. It causes the problems of shortage and overstock. In the proposed Fuzzy Inventory Control (FIC) system, both demand and availability of supply are considered and described by linguistic terms. Then, the developed fuzzy rules are used to extract the fuzzy order quantity and the fuzzy reorder point continuously. The model is more effective than the conventional approach due to adjustment of both order quantity and reorder point. A time step simulation is used to analyze the results of different types of inventory lot-sizing model. Inventory costs of the proposed fuzzy inventory system are compared with existing models based on historical data of a case study factory. It found that FIC system can obtain extremely lower cost than the conventional stochastic and dynamic lot-sizing models. © 2013 Springer Science+Business Media Dordrecht.