Jawa-Madura-Bali (JMB) electric power system is the largest electric power system in Indonesia, consuming more than 75% of the total power demand across the country. Therefore, most of the electric consumers in this region expect higher reliability than other areas in Indonesia. However, the national government applies a flat and uniform electrical tariff to the consumers. To justify any investment that satisfies higher reliability expectations, an indicator that defines reliability and financial measure is needed, namely the Value of Lost Load (VoLL). The calculation of VoLL has been conducted through different approaches and methods. This paper compares the approaches and methods of VoLL considering the availability of data and its role to justify the economic feasibility of new investments. The final recommendation for VoLL calculation was conducted on JMB electric power system using the Monte-Carlo approach to satisfy several uncertainty parameters.