![FAR_vs_BCR](https://upload.wikimedia.org/wikipedia/commons/0/05/FAR_vs_BCR.svg)
Floor area ratio (FAR) is the
ratio
In mathematics, a ratio shows how many times one number contains another. For example, if there are eight oranges and six lemons in a bowl of fruit, then the ratio of oranges to lemons is eight to six (that is, 8:6, which is equivalent to the ...
of a building's total
floor area
In architecture, construction, and real estate, floor area, floor space, or floorspace is the area (measured as square feet or square metres) taken up by a building or part of it. The ways of defining "floor area" depend on what factors of the buil ...
(gross floor area) to the size of the piece of land upon which it is built. It is often used as one of the regulations in city planning along with the building-to-land ratio. The terms can also refer to limits imposed on such a ratio through
zoning
Zoning is a method of urban planning in which a municipality or other tier of government divides land into areas called zones, each of which has a set of regulations for new development that differs from other zones. Zones may be defined for a si ...
.
Written as a formula, FAR = .
Lower maximum-allowed floor area ratios are linked to lower land values and lower housing density.
Terminology
Floor Area ratio is sometimes called floor space ratio (FSR), floor space index (FSI), site ratio or plot ratio.
The difference between FAR and FSI is that the first is a ratio, while the latter is an index.
Index numbers are values expressed as a percentage of a single base figure. Thus an FAR of 1.5 is translated as an FSI of 150%.
Regional variation
The terms most commonly used for this measurement vary from one country or region to the next.
In Australia ''floor space ratio'' (FSR) is used in
New South Wales
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and ''plot ratio'' in
Western Australia
Western Australia (commonly abbreviated as WA) is a state of Australia occupying the western percent of the land area of Australia excluding external territories. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to th ...
.
In
France
France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of overseas regions and territories in the Americas and the Atlantic, Pacific and Indian Oceans. Its metropolitan area ...
''coefficient d'occupation des sols'' (COS) is used.
In
India
India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...
''floor space index'' (FSI) and ''floor area ratio'' (FAR) are both used.
In the
United Kingdom
The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the European mainland, continental mainland. It comprises England, Scotlan ...
and
Hong Kong
Hong Kong ( (US) or (UK); , ), officially the Hong Kong Special Administrative Region of the People's Republic of China (abbr. Hong Kong SAR or HKSAR), is a city and special administrative region of China on the eastern Pearl River Delta i ...
both ''plot ratio'' and ''site ratio'' are used.
In
Singapore
Singapore (), officially the Republic of Singapore, is a sovereign island country and city-state in maritime Southeast Asia. It lies about one degree of latitude () north of the equator, off the southern tip of the Malay Peninsula, bor ...
the terms ''plot ratio'' and ''gross plot ratio'' (GPR) are more commonly used.
In the
United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territori ...
and
Canada
Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...
, ''floor space ratio'' (FSR) and ''floor area ratio'' (FAR) are both used.
Use ratios are used as a measure of the density of the site being developed. High FAR indicates a dense construction. The ratio is generated by dividing the building area by the parcel area, using the same units.
History
One of the purposes of the
1916 zoning ordinance of New York City was to prevent tall buildings from obstructing too much light and air. The 1916 zoning ordinance sought to control building size by regulating height and setback requirements for towers. In 1961, a revision to the zoning ordinance introduced the concept of floor area ratio (FAR). Buildings built before 1961 often have FARs that would be unachievable today, such as the
Empire State Building which has an FAR of 25 - meaning that it earns considerably greater rent than a newer building on the same land could hope for.
Purpose and use
The floor area ratio (FAR) can be used in
zoning
Zoning is a method of urban planning in which a municipality or other tier of government divides land into areas called zones, each of which has a set of regulations for new development that differs from other zones. Zones may be defined for a si ...
to limit
urban density
Urban density is a term used in urban planning and urban design to refer to the number of people inhabiting a given urbanized area. As such it is to be distinguished from other measures of population density. Urban density is considered an import ...
. While it directly limits building density, indirectly it also limits the number of people that a building can hold, without controlling a building's external shape.
For example, if lot must adhere to a 0.1 FAR, then the total area of all floors in all buildings on the lot must be no more than one-tenth the area of the parcel itself. In other words, if the lot was 10,000 sq. ft, then the total floor area of all floors in all buildings must not exceed 1,000 sq. ft.
An architect can plan for either a single-story building consuming the entire allowable area in one floor, or a
multi-story building
A building, or edifice, is an enclosed structure with a roof and walls standing more or less permanently in one place, such as a house or factory (although there's also portable buildings). Buildings come in a variety of sizes, shapes, and funct ...
that rises higher above the plane of the land, but which must consequently result in a smaller footprint than would a single-story building of the same total floor area. By combining the horizontal and vertical limits into a single figure, some flexibility is permitted in
building design
Building design refers to the broadly based architectural, engineering and technical applications to the design of buildings. All building projects require the services of a building designer, typically a licensed architect. Smaller, less complica ...
, while achieving a hard limit on at least one measure of overall size. One advantage to fixing this parameter, as opposed to others such as height, width, or length, is that floor area correlates well with other considerations relevant to zoning regulation, such as total parking that would be required for an
office building
An office is a space where an organization's employees perform administrative work in order to support and realize objects and goals of the organization. The word "office" may also denote a position within an organization with specific dut ...
, total number of units that might be available for residential use, total load on
municipal services, etc. The amounts of these things tend to be constant for a given total floor area, regardless of how that area is distributed horizontally and vertically. Thus, many jurisdictions have found it unnecessary to include hard height limitations when using floor area ratio calculations.
Common exclusions to the total calculation of square footage for the purpose of floor area ratio (FAR) include unoccupied areas such as mechanical equipment floors, basements exclusively used for parking, stair towers, elevator shafts, and parking garages.
Japan
Japan has extensively adopted the floor area ratio in the zoning system since 1970.
India
In India FAR and FSI are both used. FAR regulations vary from city to city and generally it is from 1.3 to 3.25. In Mumbai 1.33 is the norm but higher FSI is allowed along the Metro rail line and slum areas like
Dharavi
Dharavi is a locality in Mumbai, Maharashtra, India, considered to be one of the world's largest slums. Dharavi has an area of just over and a population of about 1,000,000. With a population density of over , Dharavi is one of the most dens ...
. In Bangalore, 40 feet streets allow only an FAR of 1.75 but 100 feet streets allow 3.25 FAR.
Impact on land value
FAR has a major impact on the value of the land. Higher allowable FAR yields higher land value.
A 2022 study found that lower maximum-allowed FAR in New York City led to lower land value and lower density.
Criticism
Andres Duany et al. (2000) note:
# Abdicating to floor area ratios (market forces) is the opposite of aiming a community toward something more than the sum of its parts.
# FAR, a poor predictor of physical form, should not be used when the objective is to conserve and enhance neighborhood character; whereas traditional design standards (height, lot coverage and setbacks or build-to lines) enable anyone to make reasonably accurate predictions, recognize violations, and feel secure in their investment decisions.
# If FAR is carelessly combined with traditional setbacks, assembled lots have a considerable advantage over individual lots, which has a negative effect on fine-grained cities and the diversity of ownership.
Clarifying Duany's second criticism in reference to "lot coverage": If localities seek to regulate density through floor area ratio, the logical consequence is to encourage expansive one story building with less green space, as single story construction is less expensive than multi-story construction on a per square foot basis. On the other hand, if density is regulated by building coverage ratio (a.k.a. lot coverage or site coverage
) then green space can be preserved and multi-story construction becomes financial advantageous. This outcome is demonstrated in the illustration comparing FAR to BCR.
Footnotes
References
* Meriam, Dwight (2004). ''The Complete Guide to Zoning''. McGraw-Hill.
* Birch, Eugenie L. (2009). "The Urban and Regional Planning Reader". Routledge. {{ISBN, 0-415-31997-8
External links
An explanation of the floor area ratioby
J.H. Crawford
Complete information on FSI or floor area ratiob
Civil Site
Urban studies and planning terminology
Real property law
Engineering ratios
de:Maß der baulichen Nutzung#Geschossflächenzahl (GFZ)