Increased demand for fuel oil (BBM) resulted in a decrease in fossil fuel reserves. Many methods are used to find alternative energy sources, new and cheap. Biodiesel is an alternative and renewable energy source obtained from vegetable and animal oil. Biodiesel has biodegradable properties and, is environmentally friendly. However, vegetable oil still has weaknesses, one of which has a high viscosity. To improve the viscosity, one of them is by mixing vegetable oil with other types of vegetable oil. This study, aims to determine the effect of variations in the composition of the mixtutre of calophyllum inophyllum oil and, used cooking oil on the characteristics of biodiesel (density, viscosity, flash point and heating value). In this study, the method used to make biodiesel is by degumming, esterification and transesterification. The variation in composition between calophyllum inophyllum oil and used cooking oil is 0:100, 10:90, 20:80, 30:70, 40:60, 50:50, 60:40, 70:30, 80:20, 90:10, 100:0 (%). The results of the research data can be concluded that the value of density, viscosity and flash point increases with increasing composition of calophyllum inophyllum oil, but with increasing composition of calophyllum inophyllum oil in the mixture results in a decrease in the heating value. The most optimal composition of MN20:MJ80 because it meets SNI 7182-2015 standards.