In this present study, a single period inventory problem is inquired with the aid of fuzzy numbers and credibility theory. A fuzzy expected value model is designed through the concept of credibility expected value criterion. The necessity of fuzzy expected value model is to determine the optimal order quantity so that the total cost becomes minimal. An iteration programming model is developed to calculate the expected value of the fuzzy credibility function. Moreover, a numerical illustration is also provided to strengthen the validity of the proposed algorithm. © 2019 Author(s).