The main activity of a bank is to finance the required funds through several kinds of deposits and allocate them to the bank customers as credits, loans and investments. Although the emphasis is on banks’ fees, but the profit consists a major part of a bank total returns. Accordingly, in order to manage bank funds in effective and efficient manners, the managers need to have precise information about the cost of their services. This paper is to calculate and compare the cost of bank facilities and loans under two different traditional and activity based costing (ABC) methods. For this purpose, first we designed an ABC model to calculate the cost of each of facilities and loans (under Islamic contracts) in the central branch of the Export Development Bank of Iran. Secondly, we calculated costs of loans and facilities using both the traditional and the ABC methods. Finally, we compared the costs and analyzed the results. The results show significant differences among different kinds of facilities and loans under two costing methods. The results changed the managers’ viewpoints about the cost and profit margin of each banking service they provide.