Technology · Regulation

Floor Area Ratio (FAR/FSI)

20th c. · USA / Japan
diagrams of permitted building envelopes from New York's 1916 zoning resolution, the bulk-control regime that floor-area ratio later replaced
diagrams of permitted building envelopes from New York's 1916 zoning resolution, the bulk-control regime that floor-area ratio later replaced · Public domain · New York City Commission on Building Districts and Restrictions

What it is

Floor Area Ratio, known as Floor Space Index in much of Asia, is the ratio of a building's total floor area to the area of its plot, so an FAR of 3 permits three times the lot's area in floor space. It became a standard 20th-century zoning control in the United States and Japan, regulating density by capping how much can be built rather than dictating exact form. The same ratio can produce a tall slender tower or a low bulky block, leaving designers some freedom within a fixed quantum of floor space.

Why it matters

FAR is a quiet but decisive lever: it sets how intensively land can be used and therefore directly shapes skylines, densities and land value. Adjusting it is one of the most powerful and contested moves available to planners managing growth.

Plans it shaped

See it on the timeline →
hub.toekom.st — History of Urbanism · an interactive timeline of 850 planned cities across 6,000 years.