This report explains RE-ZIP’s emissions calculation and reporting tool, used to assess the environmental impact of their reusable packaging solutions against single-use options made of plastic, paper, and cardboard. It describes the tool’s data sources, assumptions, and life cycle approach, detailing its alignment with ISO 14040/14044 standards and clarifying any deviations. The tool aims to provide transparency and accuracy in reporting emissions for RE-ZIP’s European take-back packaging schemes.