Determination of the amount of refrigerant in a vapor compression refrigeration system requires several approaches depending on the design and installation of the piping on each refrigeration component. For chiller systems or other packaged systems that are already loaded with refrigerant and do not require piping installation in the refrigeration system, the amount of refrigerant that is loaded into the unit is based on testing at the factory. Optimization of the amount can be done when the test is carried out in the laboratory setting and the chiller is operated with the target capacity and the performance. However, for chillers that have been installed on-site and are not in the design condition, the amount of refrigerant that must be input varies greatly to obtain optimum conditions. In this research, we will calculate the amount of hydrocarbon refrigerant R290 that must be done to achieve the most optimum or efficient conditions, in the 56 TR capacity chiller system that is installed at the Makara Art Center, Universitas Indonesia. The use of refrigerants, especially the hydrocarbon type R290, is expected to have the least amount of refrigerant possible, so it is important to determine the lowest charging with the best efficiency. The chiller system is also installed with the addition of the LSHX component which in previous studies showed the possibility of decreasing the contents of R290The refrigerant charge reduction from its optimum amount decreases the system’s efficiency. The reduction of refrigerant charge of 3.3% results in COP decrease up to 3.9%. It is then imperative that proper charging as well as minimizing leaks is important to keep the chiller works at its maximum efficiency.