The banking system has a direct and mutual relationship with economic growth. Therefore, increasing the efficiency of banks would have an impact on sustainable economic growth. There are various definitions of efficiency. Efficiency can be discussed from technical, data allocation, and economic aspects. In this area, there are both simple and shallow methods and more advanced and complete methods. In many firms and factories, the final product is completely defined and tangible. However, in banks, the final product is not clearly defined, and it depends on the role we define for banks. There are two major definitions for the role of banks; one considers banks as financial intermediaries, while the other defines banks as producers of banking services. If we consider the first definition, the inputs or production factors would include the workforce, capital, and deposits, and the outputs or products would include loans or other income-generating assets. If we choose the second definition, our inputs will be the workforce and capital, while the outputs will include deposits, loans, and other services. In this paper, based on each of these two roles, we calculate the efficiency of banks using the two methods of financial ratios and data envelopment analysis (DEA) and compare the two methods by discussing the advantages and disadvantages of each one.