<p><em>This paper aims to analyse cost efficiency in conventional banking. The data for this study consist of 23 banks in Indonesia period 2009-2017. Technical efficiency scores are calculated using the Stochastic Frontier Approach (SFA) model. Cost efficiency are from variable input and output.  The result show that foreign exchange banks are most cost-efficient. State-owned banks are not necessarily efficient banks. Then, bank efficiency determined by labour cost and interest cost. Higher labour cost and interest cost will increase total cost in conventional banking. So, banks tend to be less efficient. This study has not included outside variables such as macroeconomic indicators and financial banking ratios. The results of this paper will be useful for banking industry to increase the cost efficiency by controlling labour cost and interest cost.</em></p>