Acre 1797 225577208 2008-07-14T11:42:43Z Thijs!bot 1392310 robot Adding: [[ca:Acre (unitat de superfície)]] {{onesource|article|date=November 2007}} {{otheruses}} The '''acre''' is a [[Units of measurement|unit]] of [[area]] in a number of different systems, including the [[Imperial unit#Measures of area|imperial]] and [[United States customary units#Units of area|U.S. customary]] systems. The most commonly used acres today are the international acre and, in the United States, the survey acre. One international acre is equal 4046.8564224&nbsp;[[square meters|m<sup>2</sup>]]. One U.S. survey acre is equal to {{frac|62,726,400,000|15,499,969}} = 4046.8726098&nbsp;m<sup>2</sup>. [[Image:Acre over football field.svg|frame|The area of one acre (red) overlaid on an American football field]] One acre comprises 4,840 [[square yard]]s or 43,560 [[square feet]]<ref>National Institute of Standards and Technology [http://ts.nist.gov/WeightsAndMeasures/Publications/upload/h4402_appenc.pdf General Tables of Units of Measurement]</ref> (which can be easily remembered as 44,000 square feet, less 1%). Because of alternative definitions of a yard or a foot, the exact size of an acre also varies slightly. Originally, an acre was a [[selion]] of land one [[furlong]] long and one [[chain (unit)|chain]] wide. However, an acre is a measure of area, and has no particular width, length or shape. The acre is often used to express areas of land. In the [[metric system]], the [[hectare]] is commonly used for the same purpose. An acre is approximately 40% of a hectare. One acre is 90.75 yards of a 53.33-yard-wide [[American football]] field. The full field, including the end zones, covers approximately 1.32 acres. ==International acre== In 1958, the [[United States]] and countries of the [[Commonwealth of Nations]] defined the length of the international [[yard]] to be 0.9144 [[meter]]s.<ref>National Bureau of Standards. [http://geodesy.noaa.gov/PUBS_LIB/FedRegister/FRdoc59-5442.pdf Refinement of Values for the Yard and the Pound].</ref> Consequently, the international acre is exactly 4046.8564224 [[square meters]]. ==United States survey acre== The United States survey acre is approximately 4046.873 [[square meter]]s; its exact value ({{frac|4046|13,525,426|15,499,969}} m²) is based on an inch defined by 1 meter = 39.37 inches exactly, as established by the [[Mendenhall Order]]. It is the standard acre in the [[United States]], but the fractional difference from the international acre is only 40 millionths, or 4 ten-thousandths of one percent. ==Equivalence to other units of area== 1 international acre is equal to the following metric units: * 4046.8564224 [[square meter]]s * 0.40468564224 [[hectare]] 1 United States survey acre is equal to: * 4046.87261 [[square meter]]s * 0.404687261 [[hectare]] 1 acre (both variants) is equal to the following customary units: * 66 feet × 660 feet (43,560 [[square foot|square feet]]) * 1 chain x 10 chains ( 1-chain = 66 feet or 22 yards or 4 rods) * 1 acre is approximately 208.71 feet x 208.71 feet (square) * 4840 [[square yard]]s * 160 [[Perch (area)|perches]]. A perch is equal to a square [[rod (unit)|rod]] (1 square rod is 0.00625 acre) * 10 square [[chain (unit)|chain]]s * 4 [[rood]]s * A chain by a furlong (chain 22 yards, furlong 220 yards) * 0.0015625 [[square mile]] (1 square mile is equal to 640 acres) 1 international acre is equal to the following Indian unit: * 100 [[India]]n [[cent (measure)|cent]]s (1 cent is equal to 0.01 acre) == Historical origin == The word "acre" is derived from [[Old English]] ''æcer'' (originally meaning "open field", [[cognate]] to west coast Norwegian language "ækre" and [[Swedish language|Swedish]] "åker", [[German language|German]] ''Acker'', [[Latin]] ''ager'' and [[Greek language|Greek]] ''αγρος'' (''agros''). The acre was approximately the amount of land tillable by one man behind an [[ox]] in one [[day]]. This explains one definition as the area of a rectangle with sides of length one [[chain (length)|chain]] and one [[furlong]]. A long narrow strip of land is more efficient to plough than a square plot, since the plough does not have to be turned so often. The word "furlong" itself derives from the fact that it is ''one [[furrow]] long''. Before the enactment of the [[metric system]], many countries in Europe used their own official acres. These were differently sized in different countries, for instance, the historical French acre was 4221 square metres, whereas in [[Germany]] as many variants of "acre" existed as there were German states. Statutory values for the acre were enacted in England by acts of: * [[Edward I of England|Edward I]], * [[Edward III of England|Edward III]], * [[Henry VIII of England|Henry VIII]], * [[George IV of the United Kingdom|George IV]] and * [[Victoria of the United Kingdom|Victoria]] – the British [[Weights and Measures Act]] 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, [[rood]]s, and [[perch (area)|perches]]), 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. ==Customary acre== The customary acre was a measure of roughly similar size to the acre described above, but was subject to considerable local variation. However, there were more ancient measures that were also used, including [[carucate]]s, [[virgate]]s, [[bovate]]s, [[nook]]s, and farundells or farthingales. These may have been multiples of the customary acre, rather than the statute acre. ==Other acres== * '''[[Acre (Scots)|Scottish acre]]''', one of a number of [[obsolete Scottish units of measurement]] * '''[[Acre (Irish)|Irish acre]]''' ==References== {{reflist}} == See also == * [[Conversion of units]] * [[Acre-foot]] * [[Obsolete Spanish and Portuguese units of measurement]] * [[Quarter Acre]] ==External links== * [http://www.opsi.gov.uk/si/si1995/Uksi_19951804_en_2.htm The Units of Measurement Regulations 1995 (United Kingdom)] * [[Cockeyed.com]] [http://cockeyed.com/inside/acre/acre.html presents "How much is inside an acre?"] <!--noMaelgwnbot--> [[Category:Customary units in the United States]] [[Category:Imperial units]] [[Category:Real estate]] [[Category:Units of area]] [[Category:Surveying]] [[ast:Acre (unidá de superficie)]] [[bn:একর]] [[be:Акр]] [[be-x-old:Акр]] [[bs:Acre]] [[bg:Акър]] [[ca:Acre (unitat de superfície)]] [[cs:Akr]] [[da:Acre (arealenhed)]] [[de:Acre (Einheit)]] [[et:Aaker]] [[el:Έικρ]] [[es:Acre (unidad de superficie)]] [[eo:Akreo (mezurunuo)]] [[eu:Akre]] [[fr:Acre (unité)]] [[gd:Acair (talamh)]] [[gl:Acre (unidade de superficie)]] [[ko:에이커]] [[hr:Acre (jedinica)]] [[bpy:একর]] [[it:Acro]] [[he:אקר]] [[la:Ager (mensura)]] [[mk:Акра (мерна единица)]] [[ms:Ekar]] [[nl:Acre (oppervlaktemaat)]] [[ja:エーカー]] [[no:Acre (måleenhet)]] [[pl:Akr]] [[pt:Acre (unidade)]] [[ru:Акр]] [[simple:Acre]] [[sk:Aker (jednotka)]] [[sl:Aker]] [[fi:Eekkeri]] [[sv:Acre]] [[ta:ஏக்கர்]] [[vi:Mẫu Anh]] [[uk:Акр]] [[zh:英亩]]