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. 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. FAR includes all floor areas but is indifferent to their spatial distribution on the lot whereas the building coverage ratio (or lot coverage) measures building footprint on the lot but is indifferent to building height. 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 and plot ratio in Western Australia. In France coefficient d'occupation des sols (COS) is used. 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 and 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. 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