The acre is a unit of land area used in the

imperial Imperial is that which relates to an empire, emperor, or imperialism. Imperial or The Imperial may also refer to: Places United States * Imperial, California * Imperial, Missouri * Imperial, Nebraska * Imperial, Pennsylvania * Imperial, Texa ...

and US customary systems. It is traditionally defined as the area of one

chain A chain is a serial assembly of connected pieces, called links, typically made of metal, with an overall character similar to that of a rope in that it is flexible and curved in compression but linear, rigid, and load-bearing in tension. A c ...

by one furlong (66 by 660 feet), which is exactly equal to 10 square chains, of a square mile, 4,840 square yards, or 43,560 square feet, and approximately 4,047 m², or about 40% of a hectare. Based upon the international yard and pound agreement of 1959, an acre may be declared as exactly 4,046.8564224

square metre The square metre ( international spelling as used by the International Bureau of Weights and Measures) or square meter (American spelling) is the unit of area in the International System of Units (SI) with symbol m2. It is the area of a square w ...

s. The acre is sometimes abbreviated ac but is usually spelled out as the word "acre".National Institute of Standards and Technolog
(n.d.) General Tables of Units of Measurement
. Traditionally, in the Middle Ages, an acre was conceived of as the area of land that could be

plough A plough or plow ( US; both ) is a farm tool for loosening or turning the soil before sowing seed or planting. Ploughs were traditionally drawn by oxen and horses, but in modern farms are drawn by tractors. A plough may have a wooden, iron or ...

ed by one man using a team of 8 oxen in one day. The acre is still a statutory measure in the United States. Both the international acre and the US survey acre are in use, but they differ by only four parts per million (see below). The most common use of the acre is to measure tracts of land. The acre is commonly used in a number of current and former British Commonwealth countries by custom only. In a few, it continues as a statute measure, although since 2010 not in the UK itself, and not since decades ago in

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

, New Zealand and South Africa. In many of those where it is not a statute measure, it is still lawful to "use for trade" if given as supplementary information and is not used for

land registration Land registration is any of various systems by which matters concerning ownership, possession, or other rights in land are formally recorded (usually with a government agency or department) to provide evidence of title, facilitate transactions, a ...

Description

One acre equals (0.0015625) square mile, 4,840 square yards, 43,560 square feet, or about (see below). While all modern variants of the acre contain 4,840 square yards, there are alternative definitions of a yard, so the exact size of an acre depends upon the particular yard on which it is based. Originally, an acre was understood as a

selion A selion is a medieval open strip of land or a small Field (agriculture), field used for growing crops, usually owned by or rented to peasants. A selion of land was typically one furlong (660 ft) long and one chain (unit), chain (66 ft) ...

of land sized at forty

perches Perch is a common name for fish of the genus ''Perca'', freshwater gamefish belonging to the family Percidae. The perch, of which three species occur in different geographical areas, lend their name to a large order of vertebrates: the Percif ...

(660 ft, or 1 furlong) long and four perches (66 ft) wide; this may have also been understood as an approximation of the amount of land a yoke of oxen could plough in one day (a furlong being "a furrow long"). A square enclosing one acre is approximately 69.57 yards, or 208 feet 9 inches (), on a side. As a unit of measure, an acre has no prescribed shape; any area of 43,560 square feet is an acre.

US survey acres

In the international yard and pound agreement of 1959, the United States and five countries of the Commonwealth of Nations defined the international yard to be exactly 0.9144 metre. The US authorities decided that, while the refined definition would apply nationally in all other respects, the US survey foot (and thus the survey acre) would continue 'until such a time as it becomes desirable and expedient to readjust t. By inference, an "international acre" may be calculated as exactly square metres but it does not have a basis in any international agreement. Both the international acre and the US survey acre contain of a square mile or 4,840 square yards, but alternative definitions of a yard are used (see survey foot and survey yard), so the exact size of an acre depends upon the yard upon which it is based. The US survey acre is about 4,046.872 square metres; its exact value ( m²) is based on an inch defined by 1 metre = 39.37 inches exactly, as established by the Mendenhall Order of 1893. Surveyors in the United States use both international and survey feet, and consequently, both varieties of acre. Since the difference between the US survey acre and international acre (0.016 square metres, 160 square centimetres or 24.8 square inches), is only about a quarter of the size of an

A4 sheet ISO 216 is an international standard for paper sizes, used around the world except in North America and parts of Latin America. The standard defines the "A", "B" and "C" series of paper sizes, including A4, the most commonly available paper size ...

or US letter, it is usually not important which one is being discussed. Areas are seldom measured with sufficient accuracy for the different definitions to be detectable. In October 2019, US National Geodetic Survey and National Institute of Standards and Technology announced their joint intent to end the "temporary" continuance of the US survey foot, mile and acre units (as permitted by their 1959 decision, above), with effect from the end of 2022.

Spanish acre

The Puerto Rican ''

cuerda The term "cuerda" (Spanish for ''rope'') refers to a unit of measurement in some Spanish-speaking regions, including Puerto Rico, Guatemala, Cuba, Spain, and Paraguay. In Puerto Rico, the term cuerda (and "Spanish acre"''Units: C: cuerda''
Russ Rowlett. The University of North Carolina at Chapel Hill.

Use

The acre is commonly used in a number of current and former Commonwealth countries by custom, and in a few it continues as a statute measure. These include Antigua and Barbuda, American Samoa, The Bahamas, Belize, the British Virgin Islands, the

Cayman Islands The Cayman Islands () is a self-governing British Overseas Territory—the largest by population in the western Caribbean Sea. The territory comprises the three islands of Grand Cayman, Cayman Brac and Little Cayman, which are located to the ...

Dominica Dominica ( or ; Kalinago: ; french: Dominique; Dominican Creole French: ), officially the Commonwealth of Dominica, is an island country in the Caribbean. The capital, Roseau, is located on the western side of the island. It is geographically ...

, the Falkland Islands,

Grenada Grenada ( ; Grenadian Creole French: ) is an island country in the West Indies in the Caribbean Sea at the southern end of the Grenadines island chain. Grenada consists of the island of Grenada itself, two smaller islands, Carriacou and Pe ...

, Ghana, Guam, the Northern Mariana Islands, Jamaica,

Montserrat Montserrat ( ) is a British Overseas Territories, British Overseas Territory in the Caribbean. It is part of the Leeward Islands, the northern portion of the Lesser Antilles chain of the West Indies. Montserrat is about long and wide, with r ...

, Samoa,

Saint Lucia Saint Lucia ( acf, Sent Lisi, french: Sainte-Lucie) is an island country of the West Indies in the eastern Caribbean. The island was previously called Iouanalao and later Hewanorra, names given by the native Arawaks and Caribs, two Amerindian ...

St. Helena Saint Helena () is a British overseas territory located in the South Atlantic Ocean. It is a remote volcanic tropical island west of the coast of south-western Africa, and east of Rio de Janeiro in South America. It is one of three constitu ...

St. Kitts and Nevis Saint Kitts and Nevis (), officially the Federation of Saint Christopher and Nevis, is an island country and microstate consisting of the two islands of Saint Kitts and Nevis, both located in the West Indies, in the Leeward Islands chain of ...

St. Vincent and the Grenadines Saint Vincent and the Grenadines () is an island country in the Caribbean. It is located in the southeast Windward Islands of the Lesser Antilles, which lie in the West Indies at the southern end of the eastern border of the Caribbean Sea wh ...

, Turks and Caicos, the United Kingdom, the United States and the US Virgin Islands.

South Asia

In India, residential plots are measured in square feet, while agricultural land is measured in acres. In Sri Lanka, the division of an acre into 160

or 4

roods A rood or rood cross, sometimes known as a triumphal cross, is a cross or crucifix, especially the large crucifix set above the entrance to the chancel of a medieval church. Alternatively, it is a large sculpture or painting of the crucifixion ...

is common. In Pakistan, residential plots is measured in (20 = 1 = 500 sq yards) and open/agriculture land measurement is in acres (8 = 1 acre or 4 = 1 acre) and (25 acres = 1 = 200 ), and .

United Kingdom

Its use as a primary unit for trade in the United Kingdom ceased to be permitted from 1 October 1995, due to the 1994 amendment of the

Weights and Measures Act A weights and measures act is a kind of legislative act found in many jurisdictions establishing technical standards for weights and measures. Notable acts of this type include: * Various Weights and Measures Acts (UK) or the various legislative ...

,The Weights and Measures Act 1985 (Metrication) (Amendment) Order 1994
HM Government, 1995 where it was replaced by the hectare though its use as a supplementary unit continues to be permitted indefinitely. This was with exemption of

Land registration Land registration is any of various systems by which matters concerning ownership, possession, or other rights in land are formally recorded (usually with a government agency or department) to provide evidence of title, facilitate transactions, a ...

, which records the sale and possession of land, in 2010

HM Land Registry His Majesty's Land Registry is a non-ministerial department of His Majesty's Government, created in 1862 to register the ownership of land and property in England and Wales. It reports to the Department for Business, Energy and Industrial Strategy ...

ended its exemption. The measure is still used to communicate with the public, and informally (non-contract) by the farming and property industries.

Equivalence to other units of area

1 international acre is equal to the following metric units: *0.40468564224 hectare (A square with 100 m sides has an area of 1 hectare.) *4,046.8564224 square metres (or a square with approximately 63.61 m sides) 1 United States survey acre is equal to: *0.404687261 hectare *4,046.87261 square metres (1 square kilometre is equal to 247.105 acres) 1 acre (both variants) is equal to the following customary units: *66 feet × 660 feet (43,560 square feet) *10 square

chains A chain is a serial assembly of connected pieces, called links, typically made of metal, with an overall character similar to that of a rope in that it is flexible and curved in compression but linear, rigid, and load-bearing in tension. A c ...

(1 chain = 66 feet = 22 yards = 4 rods = 100 links) *1 acre is approximately 208.71 feet × 208.71 feet (a square) *4,840 square yards *43,560 square feet *160

. A perch is equal to a square

rod Rod, Ror, Ród, Rőd, Rød, Röd, ROD, or R.O.D. may refer to: Devices * Birch rod, made out of twigs from birch or other trees for corporal punishment * Ceremonial rod, used to indicate a position of authority * Connecting rod, main, coupling, ...

(1 square rod is 0.00625 acre) *4

*A furlong by a chain (furlong 220 yards, chain 22 yards) *40 rods by 4 rods, 160 rods² (historically fencing was often sold in 40 rod lengths) * (0.0015625) square mile (1 square mile is equal to 640 acres) Perhaps the easiest way for US residents to envision an acre is as a rectangle measuring 88 yards by 55 yards ( of 880 yards by of 880 yards), about the size of a standard American football field. To be more exact, one acre is 90.75% of a 100-yd-long by 53.33-yd-wide American football field (without the end zone). The full field, including the end zones, covers about . For residents of other countries, the acre might be envisioned as rather more than half of a football pitch. It may also be remembered as 1% short of 44,000 square feet.

Historical origin

The word ''acre'' is derived from

Old English Old English (, ), or Anglo-Saxon, is the earliest recorded form of the English language, spoken in England and southern and eastern Scotland in the early Middle Ages. It was brought to Great Britain by Anglo-Saxon settlement of Britain, Anglo ...

originally meaning "open field",

cognate In historical linguistics, cognates or lexical cognates are sets of words in different languages that have been inherited in direct descent from an etymology, etymological ancestor in a proto-language, common parent language. Because language c ...

with west coast Norwegian , Icelandic ,

Swedish Swedish or ' may refer to: Anything from or related to Sweden, a country in Northern Europe. Or, specifically: * Swedish language, a North Germanic language spoken primarily in Sweden and Finland ** Swedish alphabet, the official alphabet used by ...

, German , Dutch , Latin , Sanskrit , and Greek (). In English, an obsolete variant spelling was ''

aker Aker may refer to: Places * Aker, Norway, a geographic area in Oslo and a former municipality in Norway * Vestre Aker, a district of Oslo within former Aker municipality * Nordre Aker, a district of Oslo within former Aker municipality * Aker Br ...

''. According to the

Act on the Composition of Yards and Perches The Composition of Yards and Perches ( la, Compositio Ulnarum et Perticarum) or the Statute of Ells and Perches was a medieval English statute defining the length of the barleycorn, inch, foot, yard, and perch, as well as the area of the acre. ...

, dating from around 1300, an acre is "40 perches

s] in length and four in breadth", meaning 220 yards by 22 yards. As detailed in the box on the right, an acre was roughly the amount of land tillable by a yoke of oxen in one day. Before the enactment of the metric system, many countries in Europe used their own official acres. In France, the was used only in Normandy (and neighbouring places outside its traditional borders), but its value varied greatly across Normandy, ranging from 3,632 to 9,725 square metres, with 8,172 square metres being the most frequent value. But inside the same of Normandy, for instance in pays de Caux, the farmers (still in the 20th century) made the difference between the (68 ares, 66 centiares) and the (56 to 65 ca). The Normandy was usually divided in 4 (

) and 160 square , like the English acre. The Normandy was equal to 1.6 , the unit of area more commonly used in Northern France outside of Normandy. In Canada, the Paris used in Quebec before the metric system was adopted is sometimes called "French acre" in English, even though the Paris and the Normandy were two very different units of area in ancient France (the Paris became the unit of area of French Canada, whereas the Normandy was never used in French Canada). The German word for acre is . There were many variants of the , differing between the different German territories: Statutory values for the acre were enacted in England, and subsequently the United Kingdom, by acts of: *

Edward I Edward I (17/18 June 1239 – 7 July 1307), also known as Edward Longshanks and the Hammer of the Scots, was King of England and Lord of Ireland from 1272 to 1307. Concurrently, he ruled the duchies of Aquitaine and Gascony as a vassal o ...

Edward III Edward III (13 November 1312 – 21 June 1377), also known as Edward of Windsor before his accession, was King of England and Lord of Ireland from January 1327 until his death in 1377. He is noted for his military success and for restoring r ...

Henry VIII Henry VIII (28 June 149128 January 1547) was King of England from 22 April 1509 until his death in 1547. Henry is best known for his six marriages, and for his efforts to have his first marriage (to Catherine of Aragon) annulled. His disa ...

* George IV * Queen Victoria – the British

of 1878 defined it as containing 4,840 square yards. Historically, the size of farms and landed estates in the United Kingdom was usually expressed in acres (or acres, roods, and

), even if the number of acres was so large that it might conveniently have been expressed in square miles. For example, a certain landowner might have been said to own 32,000 acres of land, not 50 square miles of land. The acre is related to the square mile, with 640 acres making up one square mile. One mile is 5280 feet (1760 yards). In western Canada and the western United States, divisions of land area were typically based on the square mile, and fractions thereof. If the square mile is divided into quarters, each quarter has a side length of mile (880 yards) and is square mile in area, or 160 acres. These subunits would typically then again be divided into quarters, with each side being mile long, and being of a square mile in area, or 40 acres. In the United States, farmland was typically divided as such, and the phrase "the back 40" would refer to the 40-acre parcel to the back of the farm. Most of the

Canadian Prairie Provinces The Canadian Prairies (usually referred to as simply the Prairies in Canada) is a region in Western Canada. It includes the Canadian portion of the Great Plains and the Prairie Provinces, namely Alberta, Saskatchewan, and Manitoba. These provin ...

and the US Midwest are on square-mile grids for surveying purposes.

Legacy acres

* Customary acre – The customary acre was roughly similar to the Imperial acre, but it was subject to considerable local variation similar to the variation in carucates, virgates, bovates, nooks, and farundels. These may have been multiples of the customary acre, rather than the statute acre. * Builder's acre = an even or , used in US real-estate development to simplify the math and for marketing. It is nearly 10% smaller than a survey acre, and the discrepancy has led to lawsuits alleging misrepresentation. *

Scottish acre A Scottish or Scots acre () was a land measurement used in Scotland. It was standardised in 1661. When the Weights and Measures Act of 1824 was implemented the English System was standardised into the Imperial System and Imperial acres were impose ...

= 1.3 Imperial acres (5,080 m², an obsolete Scottish measurement) *

Irish acre Irish measure or plantation measure was a system of units of land measurement used in Ireland from the 16th century plantations until the 19th century, with residual use into the 20th century. The units were based on " English measure" but us ...

= * Cheshire acre = * Stremma or Greek acre ≈ 10,000 square Greek feet, but now set at exactly 1,000 square metres (a similar unit was the zeugarion) *

Dunam A dunam ( Ottoman Turkish, Arabic: ; tr, dönüm; he, דונם), also known as a donum or dunum and as the old, Turkish, or Ottoman stremma, was the Ottoman unit of area equivalent to the Greek stremma or English acre, representing the amount ...

or Turkish acre ≈ 1,600 square Turkish paces, but now set at exactly 1,000 square metres (a similar unit was the çift) * Actus quadratus or Roman acre ≈ 14,400 square Roman feet (about 1,260 square metres) *

God's Acre God's Acre is a churchyard, specifically the burial ground. The word comes from the German ''Gottesacker'' (''Field of God''), an ancient designation for a burial ground. The use of "Acre" is related to, but not derived from the unit of measureme ...

– a synonym for a churchyard. * Long acre the grass strip on either side of a road that may be used for illicit grazing. *

Town acre In urban planning, the grid plan, grid street plan, or gridiron plan is a type of city plan in which streets run at right angles to each other, forming a grid. Two inherent characteristics of the grid plan, frequent intersections and orthogona ...

was a term used in early 19th century in the planning of towns on a

grid plan In urban planning, the grid plan, grid street plan, or gridiron plan is a type of city plan in which streets run at right angles to each other, forming a grid. Two inherent characteristics of the grid plan, frequent intersections and orthogona ...

, such as Adelaide, South Australia and Wellington,

New Plymouth New Plymouth ( mi, Ngāmotu) is the major city of the Taranaki region on the west coast of the North Island of New Zealand. It is named after the English city of Plymouth, Devon from where the first English settlers to New Plymouth migrated. ...

and Nelson in New Zealand. The land was divided into plots of an Imperial acre, and these became known as town acres.

Notes

References

External links

The Units of Measurement Regulations 1995 (United Kingdom)
{{United States Customary Units Customary units of measurement in the United States Imperial units Surveying Units of area