In microeconomics, economies of density are cost savings resulting from spatial proximity of suppliers or providers. Typically higher population densities allow synergies in service provision leading to lower unit costs.

Economies of density is efficiency gained by dense urban environments. Urban environments are generally more efficient for logistics and transport. They are also efficient for employment as workers living in a large city can more easily switch jobs without having to relocate.

Population or employment density is often used as a summary statistic to describe the spatial concentration of economic activity. In this context, density is commonly defined as the number of individuals per unit geographic area.