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Acre

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This article is about the unit of area measure. For other uses, seeAcre (disambiguation).
"Acres" redirects here. For the surname, seeAcres (surname).

acre
Onehectare,with an acre represented as the lower white-and-yellow checkered region
General information
Unit systemUS customary units,Imperial units
Unit ofarea
Symbolac, acre
Conversions
1 acin...... is equal to...
SI units= 4,046.8564224 m2
US customary, Imperial≡ 4,840 sq yd
≡1⁄640sq mi
Image comparing the acre (the small pink area at lower left) to other units. The entire yellow square is onesquare mile;the dark blue area at right represents 100 acres.

Theacre(/ˈeɪkər/AY-kər) is aunitof land area used in theBritish imperialand theUnited States customarysystems. It is traditionally defined as the area of onechainby onefurlong(66 by 660feet), which is exactly equal to 10 square chains,1⁄640of a square mile, 4,840 square yards, or 43,560 square feet, and approximately 4,047 m2,or about 40% of ahectare.Based upon theinternational yard and pound agreement of 1959,an acre may be declared as exactly 4,046.8564224square metres.The acre is sometimes abbreviatedac[1]but is usually spelled out as the word "acre".[2]

Traditionally, in theMiddle Ages,an acre was conceived of as the area of land that could beploughedby one man using a team of eightoxenin one day.[3]

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 used in many established and formerCommonwealth of Nationscountries by custom. In a few, it continues as astatute measure,although not since 2010 in the UK, and not for decades inAustralia,New Zealand,andSouth Africa.In many places where it is not a statute measure, it is still lawful to "use for trade" if given as supplementary information and is not used forland registration.

Description[edit]

One acre equals1⁄640(0.0015625) square mile, 4,840 square yards, 43,560 square feet,[2]or about 4,047square metres(0.4047hectares) (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 strip of land sized at fortyperches(660 ft, or 1furlong) long and four perches (66 ft) wide;[4]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" ). Asquareenclosing one acre is approximately 69.57 yards, or 208 feet 9 inches (63.61 metres), 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[edit]

In theinternational yard and poundagreement of 1959, the United States and five countries of theCommonwealth of Nationsdefined the international yard to be exactly 0.9144 metre.[5]The US authorities decided that, while the refined definition would apply nationally in all other respects, theUS survey foot(and thus the survey acre) would continue 'until such a time as it becomes desirable and expedient to readjust [it]'.[5]By inference, an "international acre" may be calculated as exactly4,046.8564224square metres but it does not have a basis in any international agreement.

Both the international acre and the US survey acre contain1⁄640of a square mile or 4,840 square yards, but alternative definitions of a yard are used (seesurvey footandsurvey 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 (4046+13,525,426/15,499,969m2) is based on an inch defined by 1 metre = 39.37 inches exactly, as established by theMendenhall Orderof 1893.[6]Surveyors in the United States use both international and survey feet, and consequently, both varieties of acre.[7]

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 anA4 sheetorUS 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.[8]

In October 2019, theUS National Geodetic Surveyand theNational Institute of Standards and Technologyannounced 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.[9][10]

Spanish acre[edit]

ThePuerto Ricancuerda(0.39 ha; 0.97 acres) is sometimes called the "Spanish acre" in the continental United States.[11]

Use[edit]

The acre is commonly used in many current and former Commonwealth countries by custom, and in a few it continues as astatute measure.These include Antigua and Barbuda,[12]American Samoa,[13]The Bahamas,[14]Belize,[15]theBritish Virgin Islands,[16]Canada,[17]theCayman Islands,[18]Dominica,[19]theFalkland Islands,[20]Grenada,[21]Ghana,[22]Guam,[23]theNorthern Mariana Islands,[24]Jamaica,[25]Montserrat,[26]Samoa,[27]Saint Lucia,[28]St. Helena,[29]St. Kitts and Nevis,[30]St. Vincent and the Grenadines,[31]Turks and Caicos,[32]the United Kingdom, the United States and theUS Virgin Islands.[33]

Republic of Ireland[edit]

In theRepublic of Ireland,the hectare is legally used underEuropean units of measurement directives;however, the acre is still widely used, especially in agriculture. (This is the standard statute acre, the same as used in the UK, not the oldIrish acrewhich was of a different size.)[34][35][36][37]

Indian subcontinent[edit]

In theRepublic of India,residential plots are measured in square feet or square metre, while agricultural land is measured in acres.[38]In Sri Lanka, the division of an acre into 160perchesor 4roodsis common.[39]

In Pakistan, residential plots are measured inkanal(20marla= 1kanal= 500 sq yards) and open/agriculture land measurement is in acres (8kanal= 1 acre or 4peli= 1 acre) andmuraba(25 acres = 1muraba= 200kanal),jerib,wiswaandgunta.[citation needed]

United Kingdom[edit]

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 theWeights and Measures Act,[40]where it was replaced by thehectare– though its use as a supplementary unit continues to be permitted indefinitely.[41]This was with the exemption ofLand registration,[40]which records the sale and possession of land,[42]in 2010HM Land Registryended its exemption.[41]The measure is still used to communicate with the public,[43]and informally (non-contract) by the farming and property industries.[44][45][46]

Equivalence to other units of area[edit]

The area of one acre (red) superposed on anAmerican footballfield (green) andAssociation football/soccer pitch (blue)

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:

  • 0.404687261hectare
  • 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 squarechains(1 chain = 66 feet = 22 yards = 4 rods = 100links)
  • 1 acre is approximately 208.71 feet × 208.71 feet (a square)
  • 4,840 square yards
  • 43,560 square feet
  • 160perches.A perch is equal to a squarerod(1 square rod is 0.00625 acre)
  • 4roods
  • 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[47])
  • 1⁄640(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 (1⁄10of 880 yards by1⁄16of 880 yards), about9⁄10the size of a standardAmerican 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 theend zone). The full field, including the end zones, covers about 1.32 acres (0.53 ha).

For residents of other countries, the acre might be envisioned as rather more than half of a 1.76 acres (0.71 ha)football pitch.

Historical origin[edit]

Farm-derived units of measurement:
  1. Therodis a historical unit of length equal to5+1⁄2yards. It may have originated from the typical length of a mediaevalox-goad.There are 4 rods in onechain.
  2. Thefurlong(meaning furrow length) was the distance a team of oxen could plough without resting. This was standardised to be exactly 40 rods or 10 chains.
  3. Anacrewas the amount of land tillable by one man behind one team of eight oxen in one day. Traditional acres were long and narrow due to the difficulty in turning the plough and thevalue of river front access.
  4. Anoxgangwas the amount of land tillable by one ox in a ploughing season. This could vary from village to village, but was typically around 15 acres.
  5. Avirgatewas the amount of land tillable by two oxen in a ploughing season.
  6. Acarucatewas the amount of land tillable by a team of eight oxen in a ploughing season. This was equal to 8 oxgangs or 4 virgates.

The wordacreis derived fromOld Englishæceroriginally meaning "open field",cognatewith west coast Norwegianækre,Icelandicakur,Swedishåker,GermanAcker,Dutchakker,Latinager,Sanskritajr,and Greekαγρός(agros). In English, an obsolete variant spelling wasaker.

According to theAct on the Composition of Yards and Perches,dating from around 1300, an acre is "40perches[rods] in length and four in breadth ",[48]meaning 220 yards by 22 yards.[a]As detailed in the diagram, an acre was roughly the amount of land tillable by a yoke of oxen in one day.[49]

Before the enactment of themetric system,many countries in Europe used their own official acres. In France, the traditional unit of area was thearpent carré,a measure based on the Roman system of land measurement. Theacrewas used only inNormandy(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.[clarification needed]But inside the samepaysof Normandy, for instance inpays de Caux,the farmers (still in the 20th century) made the difference between thegrande acre(68 ares, 66 centiares) and thepetite acre(56 to 65 ca).[50]The Normandyacrewas usually divided in 4vergées(roods) and 160 squareperches,like the English acre.

The Normandyacrewas equal to 1.6arpents,the unit of area more commonly used in Northern France outside of Normandy. In Canada, the Parisarpentused inQuebecbefore the metric system was adopted is sometimes called "French acre" in English, even though the Parisarpentand the Normandyacrewere two very different units of area in ancient France (the Parisarpentbecame the unit of area of French Canada, whereas the Normandyacrewas never used in French Canada).

In Germany, the Netherlands, and Eastern Europe the traditional unit of area wasMorgen.Like the acre, themorgenwas a unit of ploughland, representing a strip that could be ploughed by one man and an ox or horse in a morning. There were many variants of themorgen,differing between the different German territories, ranging from1⁄2to2+1⁄2acres (2,000 to 10,100 m2). It was also used inOld Prussia,in the Balkans,Norway,andDenmark,where it was equal to about two-thirds acre (2,700 m2).

Statutory values for the acre were enacted in England, and subsequently the United Kingdom, by acts of:

Historically, the size of farms and landed estates in the United Kingdom was usually expressed in acres (or acres,roods,andperches), 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 of1⁄2mile (880 yards) and is1⁄4square mile in area, or 160 acres. These subunits would typically then again be divided into quarters, with each side being1⁄4mile long, and being1⁄16of 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 theCanadian Prairie Provincesand the US Midwest are on square-mile grids for surveying purposes.

Legacy units[edit]

  • Customary acre – The customary acre was roughly similar to the Imperial acre, but it was subject to considerable local variation similar to the variation incarucates,virgates,bovates,nooks, and farundels. These may have been multiples of the customary acre, rather than the statute acre.
  • Builder's acre = an even 40,000 square feet (3,700 m2) or 200 by 200 feet (61 m × 61 m), 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.[51]
  • Scottish acre= 1.3 Imperial acres (5,080 m2,an obsoleteScottish measurement)
  • Irish acre= 7,840 square yards (6,560 m2)
  • Cheshire acre= 10,240 square yards (8,560 m2)[52]
  • Stremmaor Greek acre ≈ 10,000 squareGreek feet,but now set at exactly 1,000 square metres (a similar unit was thezeugarion)[53]
  • Dunamor Turkish acre ≈ 1,600 squareTurkish paces,but now set at exactly 1,000 square metres (a similar unit was theçift)[53]
  • Actus quadratusor Roman acre ≈ 14,400 squareRoman feet(about 1,260 square metres)
  • God's Acre– a synonym for a churchyard.[54]
  • Long acre– the grass strip on either side of a road that may be used for illicit grazing.
  • Town acrewas a term used in early 19th century in the planning of towns on agrid plan,such asAdelaide,South Australia[55][56]andWellington,New PlymouthandNelsonin New Zealand. The land was divided into plots of an Imperial acre, and these became known as town acres.[57]

See also[edit]

Notes[edit]

  1. ^22 yards is about 20 meters.

References[edit]

  1. ^Fenna, Donald (2002).Dictionary of Weights, Measures and Units.Oxford University Press. p.4.ISBN0-19-860522-6.
  2. ^abNational Institute of Standards and Technology(n.d.) General Tables of Units of Measurement.Archived26 November 2006 at theWayback Machine.
  3. ^"Manuscripts and Special Collections – Measurements".theUniversity of Nottingham.Retrieved1 August2018.
  4. ^Klein, Herbert Arthur (2012).The Science of Measurement: A Historical Survey.Courier Corporation. p. 76.ISBN978-0-486-14497-9.
  5. ^ab"Refinement of Values for the Yard and the Pound"(PDF).noaa.gov.National Bureau of Standards. 25 June 1959. Archived fromthe original(PDF)on 5 March 2020.Retrieved3 December2006.
  6. ^*Mendenhall, T.C. (6 October 1922)."The United States Fundamental Standards of Length and Mass".Science.New Series.56(1449): 337–380.Bibcode:1922Sci....56..377M.doi:10.1126/science.56.1449.377.ISSN0036-8075.JSTOR1647062.PMID17833047.Retrieved16 August2021.
  7. ^National Geodetic Survey,(January 1991),Policy of the National Geodetic Survey Concerning Units of Measure for the State Plane Coordinate System of 1983.
  8. ^Minimum Standard Detail Requirements For ALTA/NSPS Land Title Surveys.Federick, MD: American Congress on Surveying and Mapping. 2021. [The stated maximum allowable "precision" (page 2) is 2 cm and 50 parts per million. An instrument consistently measuring 2 cm short would measure the area of a one international acre square, 63.614907 m on a side, as 4044.3 square metres, 2.6 square metres less than the true value, a far greater discrepancy than the difference between the international and survey acres.]
  9. ^"NGS and NIST to Retire U.S. Survey Foot after 2022".National Geodetic Survey. 31 October 2019.Retrieved4 March2020.
  10. ^"U.S. Survey Foot: Revised Unit Conversion Factors".NIST. 16 October 2019.Retrieved4 March2020.
  11. ^Units: C: cuerda.Russ Rowlett. The University of North Carolina at Chapel Hill.
  12. ^"Gov't Gifts 'Bakka' With Half-Acre Land | Antigua Observer Newspaper".Archived fromthe originalon 4 October 2013.Retrieved14 February2014.
  13. ^"National Park of American Samoa completes two successful forest projects | Samoa News".SamoaNews.com. 15 April 2012.Retrieved14 February2014.
  14. ^Lowe, Alison (15 August 2013)."Construction underway on Old Fort School".The Nassau Guardian.Archived fromthe originalon 25 April 2019.Retrieved6 February2019.
  15. ^"2,225-acre Cobia farm proposed near Lark and Bugle Cayes | Amandala Newspaper".amandala.com.bz. 7 January 2008.Retrieved14 February2014.
  16. ^"Work continues on development".bvibeacon.com.Retrieved14 February2014.,
  17. ^"Value per acre of farm land and buildings at July 1".Statistics Canada. 13 April 2021.Retrieved11 March2023.
  18. ^"Kai drama over 50-acre development:: cayCompass.com".compasscayman.com. Archived fromthe originalon 1 March 2014.Retrieved14 February2014.
  19. ^"Dominica not meeting quota for international banana markets | Dominica News Online".dominicanewsonline.com. Archived fromthe originalon 4 October 2013.Retrieved14 February2014.
  20. ^"Farm Yarns with Elaine – Farm yarns with Elaine Turner – Part 13".penguin-news.com. Archived fromthe originalon 24 September 2015.Retrieved14 February2014.
  21. ^"Grenada Broadcast – George Grant – The Grenada Spices Industry".grenadabroadcast.com. Archived fromthe originalon 4 October 2013.Retrieved14 February2014.
  22. ^Ofori-Atta, Prince."Mortgages in Ghana: Snapping up an acre of Accra real estate".www.theafricareport.com.Retrieved31 March2018.
  23. ^"Local News | Pacific Daily News".guampdn.com. Archived fromthe originalon 1 October 2013.Retrieved14 February2014.
  24. ^"Islan Pagan".saipantribune.com.Archived fromthe originalon 17 October 2013.
  25. ^"Tropicrop Mushrooms Ltd v Saint Thomas Parish Council, etal"(PDF).Archived(PDF)from the original on 9 October 2022.
  26. ^"Beresford Allen of St. Peters Montserrat is a Wanted Man! | The Montserrat Reporter".themontserratreporter.com.Retrieved14 February2014.
  27. ^"Conflicting stories about Nu'u estate".samoaobserver.ws. Archived fromthe originalon 19 September 2018.Retrieved14 February2014.
  28. ^"The Voice – The national newspaper of St. Lucia since 1885".thevoiceslu.com. Archived fromthe originalon 4 October 2013.Retrieved14 February2014.
  29. ^"FEATURE: We built an island dream on our own St Helena | St Helena Online".sthelenaonline.org. Archived fromthe originalon 21 October 2013.Retrieved14 February2014.
  30. ^"SIDF Sinks SKN Passport Money into Christophe Harbour:: The St. Kitts-Nevis Observer".thestkittsnevisobserver.com. Archived fromthe originalon 4 October 2013.Retrieved14 February2014.
  31. ^"PM vows to spend rest of life seeking reparations – I-Witness News".iwnsvg.com. 15 March 2013.Retrieved14 February2014.
  32. ^"Government gets $8million from Emerald Cay sale".suntci.com.Retrieved14 February2014.
  33. ^"Proposed dolphin facility will enclose about 2 acres of Water Bay – News – Virgin Islands Daily News".m.virginislandsdailynews.com. Archived fromthe originalon 22 October 2013.Retrieved14 February2014.
  34. ^"'Hectacre' recognised as official area measurement ".www.farmersjournal.ie.
  35. ^"What is an acre? The history of land surveying".www.farmersjournal.ie.
  36. ^"Time to fully embrace the metric system".Irish Examiner.15 October 2011.
  37. ^"Metrication in other countries – US Metric Association".usma.org.
  38. ^"Land Measurement Units in India – Confident Group".www.confident-group.com.17 April 2020.Retrieved19 October2020.
  39. ^"What is a perch of land in Sri Lanka?".27 July 2018.Retrieved19 October2020.
  40. ^abThe Weights and Measures Act 1985 (Metrication) (Amendment) Order 1994HM Government, 1995
  41. ^ab"Explanatory memorandum to The weights and measures (metrication amendments) regulations 2009"(PDF).Legislation.gov.uk.2009.Archived(PDF)from the original on 9 October 2022.
  42. ^"Land Registration Act 2002".legislation.gov.uk.UK:The National Archives.2002.Retrieved3 August2018.
  43. ^Waddesdon Estate: about us "By purchasing the adjoining land, the estate has grown from the original 2,700 acres in 1874 to 6,000 acres in 2011."Waddesdon ManorEstate
  44. ^"Outlook and historical context".Savills.12 February 2018.
  45. ^"Amount of UK farmland put up for sale shrinks as prices fall".Financial Times.13 February 2018.Archivedfrom the original on 10 December 2022.
  46. ^"Land for Sale".farminguk.
  47. ^"ed. 842".Farmers' Bulletin.U.S. Government Printing Office: 24. 1919.
  48. ^Great Britain;Owen Ruffhead(1765).Statutes at Large.Printed by M. Baskett. p. 421.Retrieved12 February2012.It is ordained that 3grains of barleydry and round do make aninch,12 inches make 1foot,3 feet make 1 yard, 5 yards and a half make aperch,and 40 perches in length and 4 in breadth make an acre.
  49. ^"acre, n.".Oxford English Dictionary.December 2011.
  50. ^Raymond Mensire,Le Patois cauchois,1939, p. 55.
  51. ^"How Much is an Acre of Land".Maximum Exposure Real Estate web site.Retrieved6 August2021.
  52. ^Holland, Robert. (1886).A glossary of words used in the County of Chester.London: Trübner for the English Dialect Society. p. 3.
  53. ^abMalcolm, Noel (1999).Kosovo: A Short History.Harper Perennial.ISBN978-0-06-097775-7.
  54. ^"Definition of GOD'S ACRE".www.merriam-webster.com.
  55. ^Elton, Jude (10 December 2013)."Light's Plan of Adelaide, 1840".Adelaidia.History Trust of South Australia.Retrieved16 January2021.
  56. ^Llewellyn-Smith, Michael (2012). "The Background to the Founding of Adelaide and South Australia in 1836".Behind the Scenes: The Politics of Planning Adelaide.University of Adelaide Press.pp. 11–38.ISBN9781922064400.JSTOR10.20851/j.ctt1sq5wvd.8.Retrieved16 January2021– viaJSTOR.
  57. ^Schrader, Ben (26 March 2015)."City planning – Early settlement planning".Te Ara Encyclopedia of New Zealand.Retrieved16 January2021.

External links[edit]

Wikisourcehas the text of the1911Encyclopædia Britannicaarticle "Acre (land measure)".
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