The focus of FUSIONS is on promoting food waste prevention by optimising food use and waste prevention strategies. In order to reduce food waste it is necessary to quantify the waste and find the reasons why it occurs. The subject of this report is quantification of food waste all along the value chain from before the material is called food (primary production and processing) until final consumption (household and food service). This report presents the work in FUSIONS on “Quantitative techniques and data integrity”. The work is based on previous FUSIONS reports being “FUSIONS Definitional Framework for Food Waste (Full Report)”, “Review of EUROSTATs reporting method and statistics”, “Report on review of (food) waste reporting methodology and practice” and the participants own experience and knowledge. This report forms an important part of the basis for the “Food waste quantification manual to monitor waste amounts and progression”. The partners BOKU, DLO, IFR, INRA, MTT, OSTFOLD, SIK, and UNIBO have participated in the work, which was led by OSTFOLD and supervised by SIK. Previous work in FUSIONS has shown that there are few studies on food waste and that the methodologies applied have not been harmonized between studies. Thus there is a great need for a harmonized methodology for monitoring of food waste. One important conclusion from this project is that there is not one single method that can be recommended for all applications. This report identifies a number of possible quantification methods that can be used, investigates their advantages and disadvantages, for what applications they should be used and present some guidelines on how to use them. The report also gives some general guidelines on how to proceed when choosing methodology. E.g. first the goal and scope must be determined. If the goal is to reduce pressure on landfills the method(s) chosen will probably be different from a study where the goal is to identify and prioritize food waste reduction measures. Another important step is to determine what data already exists. In general, the following steps must be considered: Identification (is it food waste?), measurement, recording data, collecting data, calculation of waste. The main methods studied are: Measurement, scanning, waste composition analysis, food waste diary, questionnaires, calculations based on existing statistics, interviews and surveys, and mass balances. Recommendations are given for each step in the value chain from primary production, processing & manufacturing, wholesale, retail and marketing, redistribution, food service and households (end users for food preparation and consumption). Some methods have mainly been used in one sector, e.g. scanning in retail, food waste composition analyses for households, direct measurements in production, whereas other are more commonly used in all areas, e.g. interviews and questionnaires.There is little available data on food waste in EU-28 and it might take many years to rectify this situation. One concern is that this will be a barrier towards identifying and implementing measures to reduce food waste amounts. In this report a simplified framework for quantification of food waste is suggested that can be used to fill data gaps until detailed food waste data is available.The report also gives advice on data quality, schemes to classify companies and food products, food waste prevention methodologies and waste treatment.