The electrification of East Africa followed an exceptionally uneven path. After about 50 years of relative neglect under colonial rule, the construction of hydroelectric dams moved electricity generation into the focus of late colonial development policy and became the major field of intervention for foreign donors after independence. The metrics of electricity attained a role as indicator and driver for economic growth, and therefore as a target figure in economic policy, one that was arguably not justified by their actual significance (...) in the energy landscape of East Africa. This paper analyses both the global preconditions of this shift and its local repercussions. Rather than the physical visibility of electricity in the form of large dams and high-tension lines, the paper focuses on the processes that rendered electricity ontologically visible. It traces attempts by engineers, expert advisors, or development consultants to translate the complex information associated with the generation and consumption of electricity into calculable and comparable metrics. The paper scrutinises these commensuration processes in terms of the resources and knowledge they required, the frameworks of agency they opened, and the way they fed into wider discourses of development. It asks how the metrics of electricity themselves became part of the colonial and postcolonial politics of calculation, as they increasingly came to be seen as a medium for conceiving national economies. This trend was reinforced by the ascent of development economics in the 1950s and its influence on the ontological foundations of international development cooperation and post-independence nation-building. Because of the calculability and capital-intensity of its production, electricity lent itself perfectly to an economic policy based on macroeconomic aggregates and abstract growth models. Conversely, the electricity bias of international development agencies and the national government rendered rural, non-commercial, and non-productive energy use largely invisible. (shrink)