Reliability of a distribution network is an important factor in the continuity of service to consumers. This research aims to determine the level of reliability of each feeder of a 20 kV distribution system from Batang Substation using several calculation indices, namely SAIFI (System Average Interuption Frequency Index), SAIDI (System Interaction Duration Index), and CAIDI (Customer Average Duration Index). As technology develops, calculations can be made with application software to make analysis easier. The research serves to facilitate the user to calculate the reliability value of a distribution network that was originally done manually into an automatic formula that has been entered into the operating system. This software application is made using java programming language and uses the netbeans 8.0.2 application which can be developed by future researchers. The calculation results of this application software are accurate so that it can help users in calculating reliability values more effectively and efficiently.