What is Density? Zoning Definition

Density in zoning refers to how much development is allowed on a given piece of land. For residential projects, it is most commonly measured in dwelling units per acre (du/ac). For commercial or mixed-use development, density is often expressed through Floor Area Ratio (FAR), which compares total building floor area to lot size. Zoning ordinances set maximum density limits for each district to control the scale and intensity of development.

For example, a low-density residential zone might allow up to 4 dwelling units per acre, which typically results in single-family homes on larger lots. A high-density zone might allow 40 or more units per acre, accommodating apartment buildings and condominiums. These limits directly influence housing supply, neighborhood character, infrastructure demand, and land values.

Density standards interact closely with other dimensional requirements such as setbacks, building height, lot coverage, and parking. Even if a zoning district allows high density on paper, other regulations may make it physically impossible to build to the maximum allowed number of units. This is sometimes referred to as "effective density" versus "permitted density."

Many communities are reevaluating their density standards as part of efforts to address housing shortages and affordability. Density bonuses are a common tool that allows developers to build more units than normally permitted in exchange for providing affordable housing, open space, or other public benefits. If you are planning a residential project, understanding the density limits in your zoning district is one of the first steps in determining how many units you can build.