This document introduces a methodology that enables the full-cost accounting (FCA) of the food wastage footprint. Based on the best knowledge and techniques available, FCA measures and values in monetary terms the externality costs associated with the environmental impacts of food wastage. The FCA framework incorporates several elements: market-based valuation of the direct financial costs, non-market valuation of lost ecosystems goods and services, and well-being valuation to assess the social costs associated with natural resource degradation.