Hectare

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Short description: Metric unit of area
Illustration of One Hectare.png
A visualisation of one hectare
General information
Unit systemNon-SI unit accepted for use with SI
Unit ofArea
Symbolha 
Conversions
1 ha in ...... is equal to ...
   SI base units:   104 m2
   Imperial and US customary units   11,960 sq yd
2.4711 acres
Image comparing the hectare (the small blue area at lower left) to other units. The entire yellow square is one square mile.

The hectare (/ˈhɛktɛər, -tɑːr/; SI symbol: ha) is a non-SI metric unit of area equal to a square with 100-metre sides (1 hm2), that is, 10,000 square meters (10,000 m2), and is primarily used in the measurement of land. There are 100 hectares in one square kilometre. An acre is about 0.405 hectares and one hectare contains about 2.47 acres.

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 ​1⁄100 km2 (10,000 square metres). When the metric system was further rationalised in 1960, resulting in the International System of Units (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 (1,000 m2) and are (100 m2) are not officially "accepted for use", they are still used in some contexts.

Description

Comparison of area units
Unit SI
1 ca 1 m2
1 a 100 m2
1 ha 10,000 m2
100 ha 1,000,000 m2
1 km2
non-SI comparisons
non-SI metric
0.3861 sq mi 1 km2
2.471 acre 1 ha
107,639 sq ft 1 ha
1 sq mi 259.0 ha
1 acre 0.4047 ha
Trafalgar Square has an area of about one hectare.[1]

The hectare (/ˈhɛktɛər, -tɑːr/[2]), although not a unit of SI, is the only named unit of area that is accepted for use with SI units.[3] The name was coined in French, from the Latin ārea.[4] 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,[5] 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[6] and Australia (since 1970).[7][8] However, the United Kingdom,[9] the United States, Myanmar (Burma),Cite error: Closing </ref> missing for <ref> tag

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:[10]

History

The metric system of measurement was first given a legal basis in 1795 by the French Revolution ary government. The law of 18 Germinal, Year III (7 April 1795) defined five units of measure:[14]

  • The :metre for length
  • The are (100 m2) for area [of land]
  • The stère (1 m3) for volume of stacked firewood[15]
  • The :litre (1 dm3) 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 (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".[16]

In 1972, the European Economic Community (EEC) passed directive 71/354/EEC,[17] 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

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 ​1⁄10,000 are or one square decimetre.[18] Such usage of a double prefix is non-standard. The decimilliare is roughly a four-inch-by-four-inch square.

Centiare

The centiare is one square metre.[19][20]

Deciare

The deciare (rarely used) is ten square metres.[21]

Are

The are (/ɑːr/[22] or /ɛər/[23]) is a unit of area, equal to 100 square metres (10 m × 10 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).[24] 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 sotka (Russian: сотка: 'a hundred', i.e. 100 m2 or ​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, шесть соток).

Decare

The decare or dekare (/ˈdɛkɑːr, -ɛər/) is derived from deca and are, and is equal to 10 ares or 1000 square metres. It is used in Norway [25] and in the former Ottoman areas of the Middle East and Bulgaria[26] as a measure of land area. Instead of the name "decare", the names of traditional land measures are usually used, redefined as one decare:

Conversions

Metric and British imperial/United States customary comparisons
Unit name Symbol Multiple of
preceding unit 		Fraction of
succeeding unit 		SI equivalents British imperial/United States customary
equivalents
centiare ca 0.1 da 1 m2 10.76391 sq ft
deciare da 10 ca 0.1 a 10 m2 11.95990 sq yd
are a[29] 10 da 0.1 daa 100 m2 3.95369 perches
decare daa 10 a 0.1 ha 1000 m2 0.988422 roods
hectare ha[5] 10 daa 0.01 km2 10000 m2 2.47105 acres
square kilometre km2 100 ha 1000000 m2 0.386102 sq mi
A square acre shown inside a square hectare for size comparison.

The most commonly used units are in bold.

One hectare is also equivalent to:

Unicode

The Unicode character U+33CA ㏊ SQUARE HA, in the CJK Compatibility block, is intended for compatibility with pre-existing East Asian character codes.[32] It is not intended for use in alphabetic contexts.

See also

References

  1. ↑ "Department for Environment, Food and Rural Affairs, and Rural Payments Agency; The Delays in Administering the 2005 Single Payment Scheme in England". National Audit Office. 18 October 2006. p. 27. http://www.nao.org.uk/wp-content/uploads/2006/10/05061631.pdf. 
  2. ↑ "hectare". Oxford Dictionaries. http://oxforddictionaries.com/view/entry/m_en_gb0370830#m_en_gb0370830. 
  3. ↑ Bureau international des poids et mesures (2006), The International System of Units (SI), 8th ed., http://www.bipm.org/utils/common/pdf/si_brochure_8_en.pdf, retrieved 13 February 2008  Chapter 5.
  4. ↑ Oxford English Dictionary, 1st edition s.v.
  5. ↑ 5.0 5.1 "SI Brochure, Table 6". 2014. http://www.bipm.org/en/publications/si-brochure/table6.html. 
  6. ↑ The Council of the European Communities (27 May 2009). "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". http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=CONSLEG:1980L0181:20090527:EN:PDF. 
  7. ↑ Commonwealth of Australia (1970). "Metric Conversion Act". https://parlinfo.aph.gov.au/parlInfo/search/display/display.w3p;query=Id:%22publications/tabledpapers/HPP032016003235_2%22;src1=sm1. 
  8. ↑ Metric Pioneer (2020). "Metric Pioneer". https://metricpioneer.com/australia/. 
  9. ↑ "Weights and Measures Act 1985". British Government. 1985. http://www.legislation.gov.uk/ukpga/1985/72/pdfs/ukpga_19850072_en.pdf. 
  10. ↑ Britannica.com, unit of measurement, accessed 30 October 2009
  11. ↑ Caillard, Vincent Henry Penalver; Gibb, Elias John Wilkinson (1911). "Turkey". in Chisholm, Hugh. Encyclopædia Britannica. 27 (11th ed.). Cambridge University Press. pp. 426–467; see page 442 second para. "Two categories of rent, fixed and proportional, are payable to the state by mine-owners. The fixed rent is 10 piastres per jerib (about 10,000 square metres), to be paid whether the mine is worked or not.". 
  12. ↑ Oscar van Vlijmen (11 September 2006). "Oppervlakte" (in nl). Eenheden, constanten en conversies [Units, constants and conversion]. http://home.kpn.nl/vanadovv/Opp.html. 
  13. ↑ Jacob de Gelder (1824) (in nl). Allereerste Gronden der Cijferkunst. 's-Gravenhage and Amsterdam: de Gebroeders van Cleef. p. 156. https://archive.org/details/allereerstegron00ramagoog. Retrieved 19 September 2012. 
  14. ↑ "La loi du 18 Germinal an 3 " la mesure [républicaine de superficie pour les terrains, égale à un carré de dix mètres de côté »"] (in fr). Le CIV (Centre d'Instruction de Vilgénis) – Forum des Anciens. http://aviatechno.free.fr/unites/nouveausys.php. 
  15. ↑ Thierry Thomasset. "Le stère" (in fr). Tout sur les unités de mesure [All the units of measure]. Université de Technologie de Compiègne. http://www.utc.fr/~tthomass/Themes/Unites/unites/infos/stere/Le%20stere.pdf. 
  16. ↑ "SI brochure (Chapter 4; Table 8)". International Bureau of Weights and Measures. 2006. https://www.bipm.org/documents/20126/41483022/SI-Brochure-9.pdf. 
  17. ↑ "Council Directive of 18 October 1971 on the approximation of laws of the member states relating to units of measurement, (71/354/EEC)". 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=. 
  18. ↑ Robinson, Horatio Nelson; Fish, Daniel W. (1858). 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. Ivison, Blakeman, Taylor. p. 363. https://books.google.com/books?id=QaDooblqBikC&pg=PA363. 
  19. ↑ "centiare". centiare. Dictionary.com, LLC. https://www.dictionary.com/browse/centiare. Retrieved 16 October 2019. 
  20. ↑ "centiare". centiare. Collins Publishers. https://www.collinsdictionary.com/dictionary/english/centiare. Retrieved 16 October 2019. 
  21. ↑ "deciare". deciare. Merriam-Webster, Incorporated. https://www.merriam-webster.com/dictionary/deciare. Retrieved 16 October 2019. 
  22. ↑ "are". Oxford Dictionaries. http://oxforddictionaries.com/view/entry/m_en_gb0038720?rskey=sLRO50&result=2#m_en_gb0038720. [|permanent dead link|dead link}}]
  23. ↑ "are – definition. American English definition of are by Macmillan Dictionary". Macmillandictionary.com. http://www.macmillandictionary.com/dictionary/american/are_7. 
  24. ↑ "SI brochure (8th edition)". BIPM. March 2006. http://www.bipm.org/en/si/si_brochure/. 
  25. ↑ "Decrease in total grain yield". Grain and oil seeds, area and production, 2002. Statistics Norway. http://www.ssb.no/korn_en/arkiv/art-2003-03-19-01-en.html. 
  26. ↑ "Market of agricultural land in Bulgaria". BNR Radio Bulgaria. 5 October 2010. http://www.bnr.bg/sites/en/Economy/Pages/0510Marketofagriculturalland.aspx. 
  27. ↑ Λεξικό της κοινής Νεοελληνικής (Dictionary of Modern Greek), Ινστιτούτο Νεοελληνικών Σπουδών, Θεσσαλονίκη, 1998. ISBN:960-231-085-5
  28. ↑ El-Eini, Roza I.M. (2006). "Currency and Measures". Mandated landscape: British imperial rule in Palestine, 1929–1948. Routledge. p. xxiii. ISBN 978-0-7146-5426-3. https://books.google.com/books?id=ekQOAAAAQAAJ&q=El-Eini+%22Mandated+Landscape%22. Retrieved 5 May 2009. 
  29. ↑ BS350:Part 1:1974 Conversion factors and tables Part 1. Basis of tables. Conversion factors. British Standards Institution. 1974. p. 7. 
  30. ↑ François Cardarelli (2003). Encyclopaedia of scientific units, weights, and measures: their SI equivalences and origins. London, Berlin and Heidelberg: Springer Verlag. p. 97. ISBN 1-85233-682-X. https://archive.org/details/encyclopaediaofs0000card. Retrieved 29 March 2011. "metrication malta." 
  31. ↑ "Chinese Measurements – Units of Area". On-line Chinese Tools. http://www.mandarintools.com/measures.html. 
  32. ↑ Unicode.org. "CJK Compatibility block". https://www.unicode.org/charts/PDF/U3300.pdf. 

External links



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