Hectare Explained

hectare
Standard:	Non-SI unit accepted for use with SI
Quantity:	Area
Symbol:	ha
Units1:	SI base units:
Inunits1:	10^4 m^2
Units2:	Imperial and US customary units

The hectare (; 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 1disp=outNaNdisp=out and one hectare contains about 1ha.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  km² (10,000 square metres). When the metric system was further rationalised in 1960, resulting in the International System of Units, 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

SI
1 ca	1 m^2
1 a	100 m^2
1 ha	10,000 m^2
100 ha	1,000,000 m^2 1 km^2
non-SI comparisons
non-SI	metric
0.3861 sq mi	1 km^2
2.471 acre	1 ha
107,639 sq ft	1 ha
1 sq mi	259.0 ha
1 acre	0.4047 ha

The hectare (^[1]), although not a unit of SI, is the only named unit of area that is accepted for use with SI units.^[2] The name was coined in French, from the Latin Latin: ārea.^[3] 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,^[4] 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,^[5] New Zealand and Australia (since 1970).^{[6] [7]} However, the United Kingdom,^[8] the United States, Myanmar (Burma),^{[9] [10]} and to some extent Canada, use the acre instead of the hectare for measuring surface or land area.

Some countries that underwent a general conversion from traditional measurements to metric measurements (e.g. Canada) required a resurvey when units of measure in legal descriptions relating to land were converted to metric units. Others, such as South Africa, published conversion factors which were to be used particularly "when preparing consolidation diagrams by compilation".^[11]

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:^[12]

• Jerib (Persian: جریب) in Iran
• Djerib (Turkish: cerip) in Turkey^[13]
• Gongqing in China
• Manzana in Argentina
• Bunder in the Netherlands (until 1937)^{[14] [15]}

In Mexico, land area measurements are commonly given as combinations of hectares, ares, and centiares.^[16] These are commonly written separated by a dash; for example, 1-21-00.26 ha would mean 1 hectare, 21 ares, and 0.26 centiares (12,100.26 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:^[17]

• The for length
• The are (100 m²) for area [of land]
• The stère (1 m³) for volume of stacked firewood^[18]
• The (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 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".^[19]

In 1972, the European Economic Community (EEC) passed directive 71/354/EEC,^[20] 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

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 are or one square decimetre.^[21] 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.^{[22] [23]}

Deciare

The deciare (rarely used) is ten square metres.^[24]

Are

The are (^[25] or ^[26]) is a unit of area, equal to 100 square metres, 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).^[27] 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 Russian: sotka (Russian: link=no|сотка: 'a hundred', i.e. 100 m² or 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, Russian: шесть соток).

Decare

The decare or dekare is derived from deca and are, and is equal to 10 ares or 1000 square metres. It is used in Norway^[28] and in the former Ottoman areas of the Middle East and Bulgaria^[29] as a measure of land area. The names of the older land measures of similar size are usually used, redefined as exactly one decare:

• Greek, Modern (1453-);: [[Stremma]] in Greece^[30]
• Turkish: [[Dunam]], dunum, dulum, donum, or dönüm in the Balkans, Israel, Palestine, Jordan, Lebanon, Syria, and Turkey^[31]
• Norwegian: [[Norwegian units of measurement#Area|Mål]] in Norway.

Conversions

+Metric and British imperial/United States customary comparisons	Unit name	Symbol	Multiple of preceding unit	Fraction of succeeding unit	Length of square side	SI equivalents	British imperial/United States customary equivalents
centiare	ca		0.1 da			1disp=outNaNdisp=out
deciare	da	10 ca	0.1 a			10disp=outNaNdisp=out
are	a^[32]	10 da	0.1 daa			100disp=outNaNdisp=out
decare	daa	10 a	0.1 ha			1000disp=outNaNdisp=out
hectare	ha	10 daa	0.01 km^2			10000m2
square kilometre		100 ha				1000000disp=outNaNdisp=out

The most commonly used units are in bold.

One hectare is also equivalent to:

• 1 square hectometre
• 1.008 Japanese: [[Tsubo (unit)|chō]] (Japan)
• 2.381 Arabic: [[feddan]] (Egypt)
• 6.25 Thai: [[rai (unit)|rai]] (Thailand)
• 10 Arabic: [[dunam]] or Arabic: dönüm (Middle East)^[33]
• 10 Greek, Modern (1453-);: [[stremma]]ta (Greece)
• 15 Chinese: [[Chinese units of measurement#Area|mǔ]] or 0.15 Chinese: qǐng^[34]

Unicode

The Unicode character, in the CJK Compatibility block, is intended for compatibility with pre-existing East Asian character codes.^[35] It is not intended for use in alphabetic contexts. is a combination of Japanese: ヘクタール, the Japanese translation of "hectare".

See also

• Conversion of units
• Hectometre
• Order of magnitude

External links

• Official SI website: Table 6. Non-SI units accepted for use with the International System of Units

Notes and References

1. Web site: hectare. https://web.archive.org/web/20110101110815/http://oxforddictionaries.com/view/entry/m_en_gb0370830#m_en_gb0370830. dead. 1 January 2011. Oxford Dictionaries. 24 December 2010.
2. Chapter 5.
3. Oxford English Dictionary, 1st edition s.v.
4. Web site: BIPM. SI Brochure, Table 6. 17 November 2014. 2014.
5. Web site: 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 . The Council of the European Communities . 27 May 2009 . 29 January 2010.
6. Web site: Metric Conversion Act . Commonwealth of Australia . 1970 . 14 Aug 2020.
7. Web site: Metric Pioneer . Metric Pioneer . 2020 . 14 Aug 2020.
8. Web site: Weights and Measures Act 1985. British Government. 1985. 17 December 2016.
9. Web site: Appendix G – Weights and Measures . https://web.archive.org/web/20070613023743/https://www.cia.gov/library/publications/the-world-factbook/appendix/appendix-g.html . dead . 13 June 2007 . . 2006 . . 8 August 2006.
10. Web site: MYA/01/008 Agriculture Sectore Review . Working Paper No. 6 – Agroindustry in Myanmar . https://web.archive.org/web/20130515190933/http://www.agrifoodconsulting.com/ACI/uploaded_files/project_report/project_46_364535920.pdf . 15 May 2013 . dead .
11. Web site: Instructions for the Conversions of Areas to Metric. Law Society of South Africa. November 2007. 21 January 2011. 20 March 2018. https://web.archive.org/web/20180320105433/https://www.lawsoc.co.za/webs/surveyorgeneral/2007_11_area_conversion.doc. dead.
12. https://www.britannica.com/EBchecked/topic/259196/hectare Britannica.com, unit of measurement
13. Turkey . 27 . Caillard . Vincent Henry Penalver . Gibb . Elias John Wilkinson . Elias John Wilkinson Gibb . 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. .
14. Web site: Oppervlakte. Area. Eenheden, constanten en conversies [Units, constants and conversion]. nl. Oscar van Vlijmen. 11 September 2006. 15 January 2011. 19 June 2021. https://web.archive.org/web/20210619223013/https://home.kpn.nl/vanadovv/Opp.html. dead.
15. Book: Allereerste Gronden der Cijferkunst. Jacob de Gelder. 's-Gravenhage and Amsterdam. nl. 1824. 156. de Gebroeders van Cleef. Introduction to Numeracy. 19 September 2012.
16. Web site: Superficie de terrenos . 2024-05-06 . Nueva Escuela Mexicana Digital . . es.
17. Web site: La loi du 18 Germinal an 3 " la mesure [républicaine] de superficie pour les terrains, égale à un carré de dix mètres de côté »]. fr. The law of 18 Germanial year 3 "The [Republican] measure of land area equivalent to a ten-metre square". Le CIV (Centre d'Instruction de Vilgénis) – Forum des Anciens. 2 March 2010.
18. Web site: Le stère. Tout sur les unités de mesure [All the units of measure]. fr. Thierry Thomasset. Université de Technologie de Compiègne. 21 March 2011. https://web.archive.org/web/20110721011132/http://www.utc.fr/~tthomass/Themes/Unites/unites/infos/stere/Le%20stere.pdf. 21 July 2011. dead.
19. Web site: SI brochure (Chapter 4; Table 8) . . 2006 . 28 August 2023 . dmy-all .
20. Web site: Council Directive of 18 October 1971 on the approximation of laws of the member states relating to units of measurement, (71/354/EEC). 7 February 2009. 25 April 2009. 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=. dead.
21. Book: 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 . Horatio Nelson . Robinson . Daniel W. . Fish . Ivison, Blakeman, Taylor . 1858 . 363.
22. centiare . 16 October 2019 . . Dictionary.com, LLC.
23. centiare . . . 16 October 2019.
24. deciare . 16 October 2019 . . Merriam-Webster, Incorporated.
25. Web site: are. Oxford Dictionaries. 24 December 2010.
26. Web site: are – definition. American English definition of are by Macmillan Dictionary . Macmillandictionary.com . 20 May 2012.
27. Web site: SI brochure (8th edition). March 2006. BIPM.
28. Web site: Decrease in total grain yield. Grain and oil seeds, area and production, 2002. Statistics Norway. 16 November 2010.
29. Web site: Market of agricultural land in Bulgaria . 5 October 2010 . BNR Radio Bulgaria . 16 November 2010 . dead . https://web.archive.org/web/20101022061357/http://www.bnr.bg/sites/en/Economy/Pages/0510Marketofagriculturalland.aspx . 22 October 2010 . dmy-all.
30. Λεξικό της κοινής Νεοελληνικής (Dictionary of Modern Greek), Ινστιτούτο Νεοελληνικών Σπουδών, Θεσσαλονίκη, 1998.
31. Book: El-Eini . Roza I.M. . Mandated landscape: British imperial rule in Palestine, 1929–1948 . 5 May 2009 . 2006 . . 978-0-7146-5426-3 . xxiii . Currency and Measures . https://books.google.com/books?id=ekQOAAAAQAAJ&q=El-Eini+%22Mandated+Landscape%22 .
32. Book: BS350:Part 1:1974 Conversion factors and tables Part 1. Basis of tables. Conversion factors. 1974. British Standards Institution. 7.
33. Book: Encyclopaedia of scientific units, weights, and measures: their SI equivalences and origins. registration. metrication malta.. François Cardarelli. 97. Springer Verlag. London, Berlin and Heidelberg. 2003. 1-85233-682-X. 29 March 2011.
34. Web site: Chinese Measurements – Units of Area. On-line Chinese Tools. 24 December 2010.
35. Web site: Unicode.org . CJK Compatibility block .