{{short description|Metric unit of area}} {{Infobox unit | bgcolor = | name = hectare | image = Illustration of One Hectare.svg | caption = A visualisation of one hectare | standard = Non-SI units mentioned in the SI | quantity = Area | symbol = ha | units1 = SI base units: | inunits1 = 10<sup>4</sup> m<sup>2</sup> | units2 = Imperial and US customary units | inunits2 = {{cvt|1|ha|yd2 acre|sigfig=5|disp=br|order=out|comma=gaps}} }} [[File:Comparison of units of area.png|thumb|Image comparing the hectare (the small blue area at lower left) to other units. The entire yellow square is one square mile.]] The '''hectare''' ({{IPAc-en|ˈ|h|ɛ|k|t|ɛər|,_|-|t|ɑːr}}; SI symbol: '''ha''') is a non-SI metric unit of area equal to a square with 100-metre sides (1&nbsp;hm<sup>2</sup>), that is, 10,000 square metres (10,000 m<sup>2</sup>), and is primarily used in the measurement of land. There are 100 hectares in one square kilometre. An acre is about {{convert|1.000|acre|ha|disp=out|abbr=off}} and thus one hectare is about {{convert|1.000|ha|acre|disp=out}}. [[File:St. Enda's GAA ground, Omagh - geograph.org.uk - 556880.jpg|thumb|St. Enda's GAA ground, in Omagh. The playing field used in Gaelic football and hurling is a little over a hectare in size.]] In 1795, when the metric system was introduced, the '''''are''''' was defined as 100 square metres, or one square decametre, and the hectare ("hecto-" + "are") was thus 100 ''ares'' or {{sfrac|1|100}}&nbsp;km<sup>2</sup> ({{val|10000}} square metres). When the metric system was further rationalised in 1960, resulting in the International System of Units ({{tooltip|2=in French: Système International d'Unités|SI}}), the ''are'' was not included as a recognised unit. The hectare, however, remains as a non-SI unit accepted for use with the SI and whose use is "expected to continue indefinitely". Though the dekare/decare '''daa''' ({{val|1000|u=m2}}) and '''are''' (100&nbsp;m<sup>2</sup>) are not officially "accepted for use", they are still used in some contexts.

== Description == {{anchor|table-comparison-of-area-units}} {| class="wikitable" style="float:right; padding:0 0 2em 3em; margin: .56em 0 0 .8em;" |+Comparison of area units !Unit||SI |- style="text-align:right;" |1 ca |1 m<sup>2</sup> |- style="text-align:right;" |1 a |100 m<sup>2</sup> |- style="text-align:right;" |1 ha |10,000 m<sup>2</sup> |- style="text-align:right;" |100 ha |{{val|1000000|u=m2}}<br/>1&nbsp;km<sup>2</sup> |- !colspan="2"|non-SI comparisons |- !non-SI||metric |- style="text-align:right;" |0.3861 sq mi |1&nbsp;km<sup>2</sup> |- style="text-align:right;" |2.471 acre |1 ha |- style="text-align:right;" |{{val|107639|u=sq ft}} |1 ha |- style="text-align:right;" |1 sq mi |259.0 ha |- style="text-align:right;" |1 acre |0.4047 ha |}<!-- {{Convert/list_of_units/area}} -->

[[File:Trafalgar Square, London 2 - Jun 2009.jpg|right|thumb|Trafalgar Square has an area of about one hectare.<ref name=TS> {{cite web |url = http://www.nao.org.uk/wp-content/uploads/2006/10/05061631.pdf |title = Department for Environment, Food and Rural Affairs, and Rural Payments Agency; The Delays in Administering the 2005 Single Payment Scheme in England |page=27 |publisher = National Audit Office |date = 18 October 2006 }}</ref>]]

The hectare ({{IPAc-en|ˈ|h|ɛ|k|t|ɛər|,_|-|t|ɑː|r}}<ref> {{cite web |url = http://oxforddictionaries.com/view/entry/m_en_gb0370830#m_en_gb0370830 |archive-url = https://web.archive.org/web/20110101110815/http://oxforddictionaries.com/view/entry/m_en_gb0370830#m_en_gb0370830 |url-status = dead |archive-date = 1 January 2011 |title = hectare |publisher = Oxford Dictionaries |access-date = 24 December 2010 }}</ref>), although not a unit of SI, is the only named unit of area that is accepted for use with SI units.<ref name=BIPM2006Ch5>{{citation|author= Bureau international des poids et mesures |year=2006 |url=http://www.bipm.org/utils/common/pdf/si_brochure_8_en.pdf |title=The International System of Units (SI) |version= 8th ed. |access-date=13 February 2008}} Chapter 5.</ref> The name was coined in French, from the Latin {{lang|la|ārea}}.<ref>''Oxford English Dictionary'', 1st edition [http://www.oed.com/view/Entry/10502 ''s.v.'']</ref> In practice the hectare is fully derived from the SI, being equivalent to a square hectometre. It is widely used throughout the world for the measurement of large areas of land,<ref name="sibrochuretable6">{{cite web |author1=BIPM |title=SI Brochure, Table 6 |url=http://www.bipm.org/en/publications/si-brochure/table6.html |access-date=17 November 2014 |date=2014 }}</ref> and it is the legal unit of measure in domains concerned with land ownership, planning, and management, including law (land deeds), agriculture, forestry, and town planning throughout the European Union,<ref>{{cite web | url = https://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=CONSLEG:1980L0181:20090527:EN:PDF| author = The Council of the European Communities | title = Council Directive 80/181/EEC of 20 December 1979 on the approximation of the laws of the Member States relating to Unit of measurement and on the repeal of Directive 71/354/EEC | date=27 May 2009 | access-date=29 January 2010}}</ref> South Africa, New Zealand, Australia, Canada and the United Kingdom. However, the United States and Myanmar (Burma)<ref name="World Factbook"> {{cite web |url=https://www.cia.gov/library/publications/the-world-factbook/appendix/appendix-g.html |archive-url=https://web.archive.org/web/20070613023743/https://www.cia.gov/library/publications/the-world-factbook/appendix/appendix-g.html |url-status=dead |archive-date=13 June 2007 |title=Appendix G&nbsp;– Weights and Measures |work=The World Factbook |year=2006 |publisher=CIA |access-date=8 August 2006 }}</ref><ref>{{cite web |work=MYA/01/008 Agriculture Sectore Review |url=https://www.agrifoodconsulting.com/ACI/uploaded_files/project_report/project_46_364535920.pdf#page=13 |title=Working Paper No. 6 – Agroindustry in Myanmar |archive-url=https://web.archive.org/web/20130515190933/http://www.agrifoodconsulting.com/ACI/uploaded_files/project_report/project_46_364535920.pdf |archive-date=15 May 2013 |url-status=dead }}</ref> use the acre instead of the hectare for measuring surface or land area.

In many countries, metrification redefined or clarified existing measures in terms of metric units. The following legacy units of area have been redefined as being equal to one hectare:<ref>[https://www.britannica.com/EBchecked/topic/259196/hectare Britannica.com, unit of measurement], accessed 30 October 2009</ref> * ''Jerib'' ({{langx|fa|جریب}}) in Iran * ''Djerib'' ({{langx|tr|cerip}}) in Turkey<ref name="Chisholm1911">{{Cite EB1911|wstitle= Turkey |volume= 27 |last1= Caillard |first1= Vincent Henry Penalver |last2= Gibb |first2= Elias John Wilkinson |author2-link= Elias John Wilkinson Gibb | pages = 426&ndash;467; see page 442 second para |quote=Two categories of rent, fixed and proportional, are payable to the state by mine-owners. The fixed rent is 10 piastres per ''jerib'' (about {{val|10000}} square metres), to be paid whether the mine is worked or not. }}</ref> * ''Gongqing'' ({{lang-zh|t=公頃|s=公顷|first=t|p=gōngqǐng}}) in China * ''Manzana'' in Argentina * ''Bunder'' in the Netherlands (until 1937)<ref> {{cite web |url = http://home.kpn.nl/vanadovv/Opp.html |title = Oppervlakte |trans-title = Area |work = Eenheden, constanten en conversies [Units, constants and conversion] |language = nl |author = Oscar van Vlijmen |date = 11 September 2006 |access-date = 15 January 2011 |archive-date = 19 June 2021 |archive-url = https://web.archive.org/web/20210619223013/https://home.kpn.nl/vanadovv/Opp.html |url-status = dead }}</ref><ref> {{cite book |url = https://archive.org/details/allereerstegron00ramagoog |title = Allereerste Gronden der Cijferkunst |author = Jacob de Gelder |location = 's-Gravenhage and Amsterdam |language = nl |year = 1824 |page = [https://archive.org/details/allereerstegron00ramagoog/page/n179 156] |publisher = de Gebroeders van Cleef |trans-title=Introduction to Numeracy |access-date =19 September 2012 }}</ref> In Mexico, land area measurements are commonly given as combinations of hectares, ares, and centiares.<ref>{{Cite web |last= |title=Superficie de terrenos |url=https://nuevaescuelamexicana.sep.gob.mx/detalle-recurso/35466/ |access-date=2024-05-06 |website=Nueva Escuela Mexicana Digital |publisher=Secretariat of Public Education of Mexico |language=es}}</ref> These are commonly written separated by a hyphen; for example, ''1-21-00.26 ha'' would mean 1 hectare, 21 are, and 0.26 centiare ({{val|12100.26|u=m2}}).

== History == The metric system of measurement was first given a legal basis in 1795 by the French Revolutionary government. The law of 18 Germinal, Year III (7 April 1795) defined five units of measure:<ref> {{cite web |url= http://aviatechno.free.fr/unites/nouveausys.php |title = La loi du 18 Germinal an 3 " la mesure [républicaine] de superficie pour les terrains, égale à un carré de dix mètres de côté » |language = fr |trans-title=The law of 18 Germanial year 3 "The [Republican] measure of land area equivalent to a ten-metre square" |publisher = Le CIV (Centre d'Instruction de Vilgénis)&nbsp;– Forum des Anciens |access-date = 2 March 2010 }}</ref> * The :metre for length * The are (100&nbsp;m<sup>2</sup>) for area [of land] * The stère (1&nbsp;m<sup>3</sup>) for volume of stacked firewood<ref> {{cite web |url = http://www.utc.fr/~tthomass/Themes/Unites/unites/infos/stere/Le%20stere.pdf |title = ''Le stère'' |work = Tout sur les unités de mesure [All the units of measure] |language = fr |author = Thierry Thomasset |publisher = Université de Technologie de Compiègne |access-date = 21 March 2011 |archive-url = https://web.archive.org/web/20110721011132/http://www.utc.fr/~tthomass/Themes/Unites/unites/infos/stere/Le%20stere.pdf |archive-date = 21 July 2011 |url-status = dead }}</ref> * The :litre (1&nbsp;dm<sup>3</sup>) for volumes of liquid * The gram for mass

In 1960, when the metric system was updated as the International System of Units (SI), the ''are'' did not receive international recognition. The International Committee for Weights and Measures ({{tooltip|2=in French: Comité international des poids et mesures|CIPM}}) makes no mention of the ''are'' in the 2019 edition of the SI brochure, but classifies the hectare as a "Non-SI unit accepted for use with the International System of Units".<ref> {{cite web |url=https://www.bipm.org/documents/20126/41483022/SI-Brochure-9.pdf |title=SI brochure (Chapter 4; Table 8) |publisher=International Bureau of Weights and Measures |year=2006 |access-date=28 August 2023 |df=dmy-all }}</ref>

In 1972, the European Economic Community (EEC) passed directive 71/354/EEC,<ref> {{cite web | url = http://eur-lex.europa.eu/Notice.do?mode=dbl&lang=en&lng1=en,nl&lng2=da,de,el,en,es,fr,it,nl,pt,&val=22924:cs&page=1&hwords= | title = Council Directive of 18 October 1971 on the approximation of laws of the member states relating to units of measurement, (71/354/EEC) | access-date = 7 February 2009 | archive-date = 25 April 2009 | archive-url = https://web.archive.org/web/20090425221644/http://eur-lex.europa.eu/Notice.do?mode=dbl&lang=en&lng1=en,nl&lng2=da,de,el,en,es,fr,it,nl,pt,&val=22924:cs&page=1&hwords= | url-status = dead }}</ref> which catalogued the units of measure that might be used within the Community. The units that were catalogued replicated the recommendations of the CGPM, supplemented by a few other units including the ''are'' (and implicitly the ''hectare'') whose use was limited to the measurement of land.

== Unit family == right|thumb|upright=1.35| Definition of a ''hectare'' and of an ''are'' The names ''centiare'', ''deciare'', ''decare'' and ''hectare'' are derived by adding the standard metric prefixes to the original base unit of area, the ''are''.

=== Decimilliare === The '''decimilliare''' (dma, sometimes seen in cadastre area evaluation of real estate plots) is {{sfrac|1|10,000}} are or one square decimetre.<ref>{{cite book |url=https://books.google.com/books?id=QaDooblqBikC&pg=PA363 |title=Robinson's Progressive Practical Arithmetic: Containing the Theory of Numbers in Connection with Concise Analytic and Synthetic Methods of Solution, and Designed as a Complete Text-book on this Science for Common Schools and Academies |first1=Horatio Nelson |last1=Robinson |first2=Daniel W. |last2=Fish |publisher=Ivison, Blakeman, Taylor |year=1858 |page=363 }}</ref> Such usage of a double prefix is non-standard. The decimilliare is (100&nbsp;mm)<sup>2</sup> or roughly a four-inch-by-four-inch square. (The decimilliare is smaller by approximately 3.1%.)

=== Centiare === The '''centiare''' is one square metre.<ref>{{cite dictionary |url=https://www.dictionary.com/browse/centiare |title=centiare |access-date=16 October 2019 |dictionary=Dictionary.com |publisher=Dictionary.com, LLC}}</ref><ref>{{cite dictionary |url=https://www.collinsdictionary.com/dictionary/english/centiare |title=centiare |dictionary=Collins Dictionary |publisher=Collins Publishers |access-date=16 October 2019}}</ref>

=== Deciare === The '''deciare''' (rarely used) is ten square metres.<ref>{{cite dictionary |url=https://www.merriam-webster.com/dictionary/deciare |title=deciare |access-date=16 October 2019 |dictionary=Merriam Webster Dictionary |publisher=Merriam-Webster, Incorporated}}</ref>

=== Are === {{Redirect|Are (unit)|the English verb|To be (disambiguation){{!}}To Be}} The '''are''' ({{IPAc-en|ɛː}},{{IPAc-en|ɛr}} <ref> {{cite web |url = https://ahdictionary.com/word/search.html?q=are |title = Are - The American Heritage Dictionary of the English Language |publisher = HarperCollins Publishers |access-date = 29 May 2026 }}</ref><ref>{{cite web |url=https://www.collinsdictionary.com/dictionary/english/are |title=ARE definition and meaning, Collins English Dictionary |publisher=Collins |access-date=29 May 2026 }}</ref>) is a unit of area, equal to 100 square metres ({{val|10|×|10|u=m}}), used for measuring land area. It was defined by older forms of the metric system, but is now outside the modern International System of Units (SI).<ref>{{cite web |url=http://www.bipm.org/en/si/si_brochure/ |title=SI brochure (8th edition) |date=March 2006 |publisher=BIPM }}</ref> It is still commonly used in speech to measure real estate, in particular in Indonesia, India, and in various European countries.

In Russian and some other languages of the former Soviet Union, the ''are'' is called {{lang|ru-Latn|sotka}} (сотка: 'a&nbsp;hundred', i.e. 100&nbsp;m<sup>2</sup> or {{sfrac|1|100}} hectare). It is used to describe the size of suburban dacha or allotment garden plots or small city parks where the hectare would be too large. Many Russian dachas are 6 ares in size (in Russian, {{lang|ru|шесть соток}}).

=== Decare === The '''decare''' or '''dekare''' ({{IPAc-en|ˈ|d|ɛ|k|ɑːr|,_|-|ɛər}}) is derived from ''deca'' and ''are'', and is equal to 10 ares or 1000 square metres. It is used in Norway<ref> {{cite web |url = https://www.ssb.no/en/diverse/standardtegn-i-tabeller |title = Explanation of symbols |publisher = Statistics Norway |access-date = 18 March 2026 }}</ref> and in the former Ottoman areas of the Middle East and Bulgaria<ref> {{cite web |url=http://www.bnr.bg/sites/en/Economy/Pages/0510Marketofagriculturalland.aspx |title=Market of agricultural land in Bulgaria |date=5 October 2010 |publisher=BNR Radio Bulgaria |access-date=16 November 2010 |url-status=dead |archive-url=https://web.archive.org/web/20101022061357/http://www.bnr.bg/sites/en/Economy/Pages/0510Marketofagriculturalland.aspx |archive-date=22 October 2010 |df=dmy-all }}</ref> as a measure of land area. The names of the older land measures of similar size are usually used, redefined as exactly one decare: * {{lang|el-Latn|Stremma}} in Greece<ref>Λεξικό της κοινής Νεοελληνικής (Dictionary of Modern Greek), Ινστιτούτο Νεοελληνικών Σπουδών, Θεσσαλονίκη, 1998. {{ISBN|960-231-085-5}}</ref> * {{lang|tr|Dunam, dunum, dulum, donum, or dönüm}} in the Balkans, Israel, Palestine, Jordan, Lebanon, Syria, and Turkey<ref>{{cite book|last1= El-Eini |first1= Roza I.M. |title= Mandated landscape: British imperial rule in Palestine, 1929–1948 |url= https://books.google.com/books?id=ekQOAAAAQAAJ |access-date= 5 May 2009 |year= 2006 |publisher= Routledge |isbn= 978-0-7146-5426-3 |page= xxiii |chapter= Currency and Measures |chapter-url= https://books.google.com/books?id=ekQOAAAAQAAJ&q=El-Eini+%22Mandated+Landscape%22 }}</ref> * {{lang|no|Mål}} in Norway.

== Conversions == {| class="wikitable" |- |+Metric and British imperial/United States customary comparisons !Unit name !Symbol !Multiple of <br />preceding unit !Fraction of <br />succeeding unit !Length of <br />square side !SI equivalents !British imperial/United States customary<br />equivalents |- |centiare | style="text-align:center;" |ca | | style="text-align:center;" |0.1 da | style="text-align:right;" |{{val|1|u=m}} | style="text-align:center;" |{{val|1|u=m2}} | style="text-align:center;" |{{convert|1.000000|m2|ft2|disp=out|lk=out|comma=gaps}} |- |deciare | style="text-align:center;" |da | style="text-align:center;" |10 ca | style="text-align:center;" |0.1 a | style="text-align:right;" |{{val|3.1623|u=m}} | style="text-align:center;" |{{val|10|u=m2}} | style="text-align:center;" |{{convert|10.00000|m2|yd2|disp=out|lk=out|comma=gaps}} |- |are | style="text-align:center;" |a<ref>{{cite book|title=BS350:Part 1:1974 Conversion factors and tables Part 1. Basis of tables. Conversion factors|date=1974|publisher=British Standards Institution|page=7}}</ref> | style="text-align:center;" |10 da | style="text-align:center;" |0.1 daa | style="text-align:right;" |{{val|10|u=m}} | style="text-align:center;" |{{val|100|u=m2}} | style="text-align:center;" |{{convert|100.0000|m2|sqperch|disp=out|lk=out|comma=gaps}} |- |decare | style="text-align:center;" |daa | style="text-align:center;" |10 a | style="text-align:center;" |0.1 ha | style="text-align:right;" |{{val|31.623|u=m}} | style="text-align:center;" |{{val|1000|u=m2}} | style="text-align:center;" |{{convert|1000.000|m2|rood|disp=out|lk=out|comma=gaps}} |- |'''hectare''' | style="text-align:center;" |'''ha'''<ref name="sibrochuretable6" /> | style="text-align:center;" |'''10 daa''' | style="text-align:center;" |'''0.01&nbsp;km<sup>2</sup>''' | style="text-align:right;" |'''{{val|100|u=m}}''' | style="text-align:center;" |'''{{val|10000|u=m2}}''' | style="text-align:center;" |'''{{convert|10000.00|m2|acre|disp=out|comma=gaps}}''' |- |'''square kilometre''' | style="text-align:center;" |'''{{val|u=km2}}''' | style="text-align:center;" |'''100 ha''' | | style="text-align:right;" |'''{{val|1000|u=m}}''' | style="text-align:center;" |'''{{val|1000000|u=m2}}''' | style="text-align:center;" |'''{{convert|1000000.|m2|mi2|disp=out|lk=out|comma=gaps}}''' |} [[File:Sq hectare acre.jpg|thumb|An acre shown inside a hectare for size comparison]] The most commonly used units are in '''bold'''.

One hectare is also equivalent to: * 1 square hectometre * 1.008 {{lang|ja-Latn|chō}} (Japan) * 2.381 {{lang|ar-Latn|feddan}} (Egypt) * 6.25 {{lang|th-Latn|rai}} (Thailand) * 10 {{lang|ar-Latn|dunam}} or {{lang|ar-Latn|dönüm}} (Middle East)<ref>{{cite book |url = https://archive.org/details/encyclopaediaofs0000card |url-access = registration |quote = metrication malta. |title = Encyclopaedia of scientific units, weights, and measures: their SI equivalences and origins |author = François Cardarelli |page = [https://archive.org/details/encyclopaediaofs0000card/page/97 97] |publisher = Springer Verlag |location = London, Berlin and Heidelberg |year = 2003 |isbn = 1-85233-682-X |access-date = 29 March 2011}}</ref> * 10 {{lang|el-Latn|stremmata}} (Greece) * 15 {{lang|zh-Latn|mǔ}} or 0.15 {{lang|zh-Latn|qǐng}}<ref>{{cite web |url = https://www.mandarintools.com/measures.html |title = Chinese Measurements&nbsp;– Units of Area |work = On-line Chinese Tools |access-date = 24 December 2010}}</ref>

== Unicode == The Unicode character {{unichar|33CA|SQUARE ha}}, in the CJK Compatibility block, is intended for compatibility with pre-existing East Asian character codes.<ref>{{Cite web |last=Unicode.org |title=CJK Compatibility block |url=https://www.unicode.org/charts/PDF/U3300.pdf}}</ref> It is not intended for use in alphabetic contexts. {{unichar|3336}} is a combination of {{lang|ja|ヘクタール}} ({{Transliteration|ja|hekutāru}}), the Japanese translation of "hectare".

== See also == * Conversion of units * Hectometre * Order of magnitude

== References == {{reflist|2}}

== External links == {{commons}} {{EB1911 poster|Acre (land measure)}} {{wiktionary|hectare}} * [https://web.archive.org/web/20141111155820/http://www.bipm.org/en/publications/si-brochure/table6.html Official SI website: Table 6. Non-SI units accepted for use with the International System of Units]

{{SI units}}

{{Use dmy dates|date=June 2016}}

Category:Units of area Category:Non-SI metric units