Feet
Abbreviation/Symbol:
ft
' (the prime symbol)
(Meaning ten feet can be symbolised as either 10 ft or 10')
Unit of:
Worldwide use:
Feet are used for building dimensions and height in the United States, and informally in the UK and Canada, where people still give their height in feet and inches. Almost everywhere else uses meters.
The foot is also used globally to measure altitude in the aviation industry.
To convert feet to meters multiply by 0.3048, or divide by 3 and take off a bit – 10ft is 3.048m, against 3.33 by the rough method. A foot is exactly 12 inches.
Definition:
In 1959 the international yard and pound agreement (between the United States and countries of the Commonwealth of Nations) defined a yard as being exactly 0.9144 metres, which in turn defined the foot as being exactly 0.3048 metres (304.8 mm).
The foot is primarily used in the United States, Canada, and the United Kingdom, although it is still occasionally used in other countries as well.
Origin:
It is believed that the ancient Egyptians were the first to use the foot as a unit of measurement, as they used the cubit, which was equal to the length of a forearm, and divided it into smaller units, including the foot.The foot has been used as a unit of measurement throughout much of recorded history – including in Ancient Greece and the Roman Empire – and the origin of the name is generally accepted to relate to the average size of an adult, male foot (or possibly shoe). Originally divided into sixteen component units, the Romans also divided the foot into twelve uncia – the origin of the modern English term inch.
The Roman foot, the pes, was about 29.6cm – a little shorter than the modern foot of 30.48cm.
The foot continued to be used throughout Europe for most of the last two thousand years, although national and regional variations were common. Depending on where (and when) the term foot was used, it could refer to lengths as small as 273 mm or as large as 357 mm.
The foot continued to be used throughout history, even as other units of measurement were introduced. In 1959 the foot was standardized at exactly 0.3048 meters by the international yard and pound agreement. This standardization allowed for consistency in measurements and facilitated international trade and communication.
The foot is still used in the US, for people's heights in the UK, and for aircraft altitude in most countries. Elsewhere it has been replaced by the meter.
Common references:
An association football (soccer) goal is eight feet high by eight yards (24 ft) wide.
"Six feet under" is a euphemistic phrase for burial in a grave, or more broadly a dead person is sometimes described as being "six feet under".
"Five Feet High and Rising" (a reference to flood water) was used as a song title by Johnny Cash. De La Soul subsequently titled their 1989 hit hip hop album "3 Feet High and Rising".
Usage context:
The foot is an official unit in the United States, where it is exactly 0.3048 meters, and people in the United Kingdom still use it for height. Canada recognises it as an alternative to metric.
The foot is also used globally to measure altitude in the aviation industry.
In the US, houses and apartments are sold by the square foot, with larger plots measured in acres – an acre is 43,560 square feet. Pipes, lumber and cable are sold by the foot too.