This briefing note presents the sustainability impacts of food sharing initiatives (FSIs) at the urban and peri-urban (UPU) scale in the CULTIVATE hub cities of Barcelona, Utrecht and Milan. It combines data from sustainability impact reporting with the results of FSI mapping in each city, to support policymakers, municipalities, researchers, and FSIs, to better understand the sustainability impacts created by food sharing activities. While sustainability reporting frameworks such as Global Reporting Initiative (GRI), B-Corp, and Social Return on Investment (SROI) are increasingly used by large food corporations in Europe, the contributions of other food actors, including FSIs like community gardens, community kitchens, and food redistribution projects, and smaller independent food retail operators, remain largely undocumented. Organised into six sections, this document first outlines the CULTIVATE project and the focus on food sharing. Section 2 explains the sustainability impact assessment (SIA) methodology and the aggregation and extrapolation process adopted. Section 3 presents a UPU-level comparison via a suite of sustainability impact scenarios. Section 4 then presents some illustrative impact highlights drawn from the sample of completed SIA reports. Section 5 presents insights from food retail actors, with conclusions and recommendations outlined in Section 6.