These guidelines cover three main activities: Quantifying food waste in each sector (i.e. stage) of the food chain; Combining sectorial quantifications using a common framework at national level; and, Reporting the results of the national food waste quantification study at country level in a consistent and comparable manner. The Manual is aimed principally at the Member State authorities. Its goal is to support them in developing coherent methods for acquiring national food waste data covering all sectors of the food chain. It can also be used as a reference by researchers collecting data on behalf of national authorities as well as national statistical offices. The guidelines presented in this Manual builds on previous FUSIONS reports: “FUSIONS Definitional Framework for Food Waste” (FUSIONS, 2014), “Standard approach on quantitative techniques to be used to estimate food waste levels” (FUSIONS, 2014) and the partners own experience and knowledge. The partners WRAP, DLO, IVL, and OSTFOLD RESEARCH have participated in the work, which has been led by BIO by Deloitte and supervised by SP. In addition, this Manual has been developed in close collaboration with the team of experts contributing to the World Resource Institute’s Food Loss & Waste (FLW) Standard (FLW Protocol, 2015). Although, the Manual is not in itself an operating procedure for on-site quantification of food waste (in e.g. farms, factories or restaurants), it does highlight for each sector certain quantification methodologies found to be suitable. These quantification methodologies (see appendix 3 of this Manual) are in harmony with the FLW Standard approach. The Manual begins with a presentation of key terms (chapter 2) and subsequently provides a definition of food waste (chapter 3, with further details in appendix 1) and a national approach to quantification (chapter 4). Finally, it details the approach for each sector of the food supply chain (chapters 5 to 9). Preventing food waste at a national scale enables Member States to secure economic and environmental benefits, through for instance financial savings to households or avoided GHG emissions, as well as easing pressure on water supplies and land use, by not producing and purchasing more food than is needed. The 2010 European Commission Preparatory Study on Food Waste identified a poor understanding of existing levels of food waste generation across the EU. This finding was replicated more recently by the FUSIONS project (FUSIONS, 2016), with many Members States lacking robust data on the amounts of food waste generated. This Manual responds to a need for coherent quantification, that in turn enables the development of effective food waste prevention strategies.