Intro -- Acknowledgements -- Abbreviations and acronyms -- Executive summary -- 1. Introduction -- 2. Methods -- 2.1. Conceptual framework -- 2.2. Structure of the model and key assumptions -- 3. Results -- 3.1. Illustrative examples of impact estimates -- 3.2. Country case studies -- 4. Discussion -- 4.1. Limitations -- 4.2. Data requirements -- 4.3. Policy implications -- Annex 1. Assumptions of the calculator -- Overview -- Assumptions -- Annex 2. Targeted literature review to identify empirical estimates for specific assumptions in the model -- a) CHW productivity -- b) Studies on pre-service education -- c) Studies on salary pay raises and retention -- d) Studies on in-service training and retention -- Annex 3. Approaches to estimating the relationship between HRH density and service coverage -- a) DEA for the benchmarking alternative -- b) Aggregation of four treatment service indicators into a single metric -- References.