Supermarkets are designed to pass ‘economies of scale’ on to consumers in the form of low prices and a wide choice of products. For consumers, they offer economy in time as well as money. From their origins in the USA in the 1920s, supermarkets have been low-margin, high-volume businesses. Owners worked out how to run a supermarket profitably and the equations behind these profits have not changed since the mid-twentieth century. The problem is that the economies of scale in a supermarket are achieved (at least in part) by re-locating costs to other players in food supply networks and by high levels of food waste throughout the system. In this Discussion Paper, Lisa Jack unpacks the numbers involved over a century of supermarket systems, and considers the alternatives. Is it possible to scale-down the system and still have cost-benefits? And who benefits?