Grade estimation is directed toward mineral inventory estimates for a mineral deposit. In this paper, a new uncertainty oriented methodology for global grade estimation is given and its stages are demonstrated in a step by step manner. The proposed fuzzy method uses a series of fuzzy algorithms and finally estimates the ore grades based on fuzzy interval arithmetic. The method is relatively simple, and practical especially for limited numbers of data. In addition, the uncertainties can be taken into account by using fuzzy numbers. The results show that the method can be applied in reserve estimation. (c) 2006 Elsevier Ltd. All rights reserved.