The report describes the development, implementation and results of two calculators developed as part of the ChemObs project (GEF ID 9080). The first calculator – Risk and Vulnerability – accepts site specific information for contaminated areas and outputs a relative ranking of ecological and human health risks. The second – Economic Cost of Inaction – accepts chemicals exposure data for different populations and outputs estimated attributable productivity losses in 2019 USD. The calculators were developed by the NGOs PAN-UK and Pure Earth over the period 2017–2022 and utilised by national consultants in 9 different African countries. Calculator development was based on the findings of country visits and regional workshops. Implementation was supported through a series of guidance documents, seminars and online tutorials. Revisions were made in an iterative process over the project period in response to field trials and to the comments of independent peer-reviewers.