Compare methods

	Floor Area Ratio Analysis	Housing Affordability Index
Field	Urban Studies	Urban Studies
Family	Process / pipeline	Process / pipeline
Year of origin	1916	2006
Originator	Zoning and planning practice (codified in mid-20th-century density regulation)	Housing-economics tradition (ratio measures); Michael E. Stone (residual-income approach)
Type	Ratio of total building floor area to plot/lot area	Index/ratio comparing housing cost to household income
Seminal source	Ben-Joseph, E. (2005). The Code of the City: Standards and the Hidden Language of Place Making. MIT Press. ISBN: 9780262025744	Stone, M. E. (2006). What is housing affordability? The case for the residual income approach. Housing Policy Debate, 17(1), 151–184.
Aliases	Plot Ratio Analysis, Floor Space Index, FAR Analysis, Building Bulk Ratio	Median Multiple, Housing Cost Burden Ratio, Residual Income Affordability, NAR Housing Affordability Index
Related	4	4
Summary	Floor area ratio (FAR), also called plot ratio or floor space index, is the ratio of a building's total floor area to the area of the lot it sits on, and it is the workhorse metric of zoning-based density control. A FAR of 2.0 means a building has twice as much floor space as its plot, achievable as a two-storey building covering the whole lot or a four-storey building covering half of it. Embedded in zoning codes since New York's 1916 ordinance and analysed in planning texts such as Ben-Joseph's study of urban codes, FAR analysis quantifies development intensity, sets buildable limits, and links regulation to the form and density of the built environment.	A housing affordability index summarises how the cost of housing in a city or market relates to what households can pay, condensing prices, rents and incomes into a single interpretable number. The simplest forms are ratios — the median house price divided by median income, or housing outlays as a share of income — while the residual-income approach championed by Michael Stone instead asks what is left for everything else after housing is paid. Together these measures let analysts compare affordability across places and over time, flag cost-burdened populations, and track housing stress as markets shift.