Indicators are foundational for planning, monitoring and evaluating of health services in developing countries. Most health indicators use population-based data, to enable comparison across geographical areas and over time. This paper is based on an interpretative case study on health indicators and how they are calculated and used at health facilities in Cameroon. We found that health managers at different levels of health systems do not share the same understanding of health indicators and we observed a wide-spread absence of population data. We further observed that health managers derive alternative ways of calculating indicators in the absence of population data. This paper contributes by discussing the implications of a lack of a common understanding of health indicators and the absence of population data to calculate health coverage indicators. Though this study was limited to data and program managers at district and regional levels, the findings raise issues that have wider applicability in the implementation of electronic health information system as well as how indicators such as UHC goals are calculated.