The food system has been in focus as one of the major drivers behind the environmental and climate crisis. In this context, there is a growing need for more transparent and reliable information on the environmental impacts of food production and consumption as part of the transition process towards more sustainable food systems. Stakeholders along the food supply chain are confronted with multiple requirements and systems as the demand for environmental reporting at the product, company, and country level increases all at the same time. Simultaneously, consumers are often more interested in the sustainability of the food products they consume. While there is currently a lack of coherent supranational or even national legislation regulating methodological procedures, private initiatives for the environmental and carbon labelling of food products have developed rapidly. This article finds that most labels are characterised by a lack of transparency, clarity, and comprehensibility. Examining 14 labels, mainly from the German food retail market, we found a puzzling variety of data sources and methodologies used to calculate the values and claims displayed. We highlight this variety in data sources and footprint values by looking at milk and beef as case studies.