Today, about 840 million people lack access to electricity. To effectively expand energy access, government planners need to understand and have access to data and analytical tools that capture key attributes of the unserved and under-served populations they are trying to reach. This paper introduces the methods and data used in Energy Access Explorer, an online, open-source, interactive platform that analyzes spatial data related to energy supply and demand and a population’s unique attributes. Location-specific resource availability and infrastructure data are used to indicate energy supply, and demographic data and data on the social and productive uses of electricity help visualize demand. Together, these supply and demand indicators enable more comprehensive and geographically-targeted energy planning not only for energy planning institutions but also for clean energy entrepreneurs and development finance institutions and donors.