Plot ratio

Floor area ratio (FAR) is the ratio of a building's total floor area (gross floor area) to the size of the piece of land upon which it is built. The terms can also refer to limits imposed on such a ratio through zoning.

As a formula FAR = (gross floor area) / (area of the plot)

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%.

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 and plot ratio in Western Australia.

In India floor space index (FSI) and floor area ratio (FAR) are both used.

In the United Kingdom and Hong Kong both plot ratio and site ratio are used.

In Singapore the terms plot ratio add gross plot ratio (GPR) are more commonly used.

In the United States and Canada, 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. The ratio is generated by dividing the building area by the parcel area, using the same units.

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.

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Wikipedia