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Floor area ratio (FAR) is the
ratio In mathematics, a ratio indicates 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 ...

of a building's total
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(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 Urban planning, also known as regional planning, town planning, city planning, or rural planning, is a technical and political process that is focused on the development and design A design is a plan ...
. Written as a formula, FAR = .

# 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 New South Wales (abbreviated as NSW) is a state State may refer to: Arts, entertainment, and media Literature * ''State Magazine'', a monthly magazine published by the U.S. Department of State * The State (newspaper), ''The State'' (newspape ...
and ''plot ratio'' in
Western Australia Western Australia (abbreviated as WA) is a state State may refer to: Arts, entertainment, and media Literature * ''State Magazine'', a monthly magazine published by the U.S. Department of State * The State (newspaper), ''The State'' (newspape ...

. In
India India, officially the Republic of India (Hindi Hindi (Devanagari: , हिंदी, ISO 15919, ISO: ), or more precisely Modern Standard Hindi (Devanagari: , ISO 15919, ISO: ), is an Indo-Aryan language spoken chiefly in Hindi Belt, ...

''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,Usage is mixed. The Guardian' and Telegraph' use Britain as a synonym for the United Kingdom. Some prefer to use Britain as shorth ...

and
Hong Kong Hong Kong (; , ), officially the Hong Kong Special Administrative Region of the People's Republic of China (HKSAR), is a city A city is a large human settlement.Goodall, B. (1987) ''The Penguin Dictionary of Human Geography''. London: Pe ...

both ''plot ratio'' and ''site ratio'' are used. In
Singapore Singapore (), officially the Republic of Singapore, is a sovereign state, sovereign island 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
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and
Canada Canada is a country in the northern part of North America North America is a continent A continent is any of several large landmasses. Generally identified by convention (norm), convention rather than any strict criteria, ...

, ''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 The Empire State Building is a 102-story Art Deco Art Deco, sometimes referred to as Deco, is a style of visual arts, architecture and design that first appeared in France just before World War I World War I, often abbreviated ...

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 Urban planning, also known as regional planning, town planning, city planning, or rural planning, is a technical and political process that is focused on the development and design A design is a plan ...
to limit
urban density Urban density is a term used in urban planning Urban planning, also known as regional planning, town planning, city planning, or rural planning, is a technical and political process that is focused on the development and design A design is ...
. 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 a structure with a roof and walls standing more or less permanently in one place, such as a house or factory. Buildings come in a variety of sizes, shapes, and functions, and have been adapted throughout history for a w ...
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 Architecture (Latin ''architectura ''Architectura: Zeitschrift für Geschichte der Baukunst'' is a biannual peer-reviewed Peer review is the evaluation of work by one or mor ...
, 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, organization's employees perform Business administration, administrative Work (human activity), work in order to support and realize objects and Goals, plans, action theory, goals of the organizati ...

, total number of units that might be available for residential use, total load on
municipal services Municipal services or city services refer to basic services that residents of a city A city is a large human settlement.Goodall, B. (1987) ''The Penguin Dictionary of Human Geography''. London: Penguin.Kuper, A. and Kuper, J., eds (1996) ''The S ...
, 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 Mumbai (, ; also known as Bombay , List of renamed Indian cities and states#Maharashtra, the official name until 1995) is the capital city of the Indian States and union territories of India, state of Ma ...

. 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.

# 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.

# 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