Hectare
Encyclopedia
Unit non-SI comparisons SI 1 ca 1 m2 1 a 100 m2 1 ha 10,000 m2 100 ha 1 km2 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

The hectare (icon or ˈ; SI
Si
Si, si, or SI may refer to :- Measurement, mathematics and science :* International System of Units , the modern international standard version of the metric system...

unit symbol ha) is a metric unit of area
Area
Area is a quantity that expresses the extent of a two-dimensional surface or shape in the plane. Area can be understood as the amount of material with a given thickness that would be necessary to fashion a model of the shape, or the amount of paint necessary to cover the surface with a single coat...

defined as 10,000 square metre
Square metre
The square metre or square meter is the SI derived unit of area, with symbol m2 . It is defined as the area of a square whose sides measure exactly one metre...

s (100 m by 100 m), and primarily used in the measurement of land. In 1795, when the metric system was introduced, the are was defined as being 100 square metre
Metre
The metre , symbol m, is the base unit of length in the International System of Units . Originally intended to be one ten-millionth of the distance from the Earth's equator to the North Pole , its definition has been periodically refined to reflect growing knowledge of metrology...

s and the hectare ('hecto-' + 'are') was thus 100 ares or 1/100 km2. A hectare of land is about 2.47 acres.

When the metric system was rationalised in 1960 with the introduction of the International System of Units
International System of Units
The International System of Units is the modern form of the metric system and is generally a system of units of measurement devised around seven base units and the convenience of the number ten. The older metric system included several groups of units...

(SI), the are was not included as a recognised unit. The hectare is one of the non-SI units accepted for use with the SI units.

## History

The metric system of measure was first given a legal basis in 1795 by the French Revolution
French Revolution
The French Revolution , sometimes distinguished as the 'Great French Revolution' , was a period of radical social and political upheaval in France and Europe. The absolute monarchy that had ruled France for centuries collapsed in three years...

ary government. The law of 18 Germinal, Year III
French Republican Calendar
The French Republican Calendar or French Revolutionary Calendar was a calendar created and implemented during the French Revolution, and used by the French government for about 12 years from late 1793 to 1805, and for 18 days by the Paris Commune in 1871...

(7 April 1795) defined five units of measure:
• The metre
Metre
The metre , symbol m, is the base unit of length in the International System of Units . Originally intended to be one ten-millionth of the distance from the Earth's equator to the North Pole , its definition has been periodically refined to reflect growing knowledge of metrology...

for length
• The are (100 m2) for area [of land]
• The stère
Stère
The stere or stère is a unit of volume in the original metric system equal to one cubic metre. The name was coined from the Greek στερεός stereos 'solid' in 1793 France as a metric equivalent to the cord. The stère is typically used for measuring large quantities of firewood or other cut wood,...

(1 m3) for volume of stacked firewood
• The litre
Litre
pic|200px|right|thumb|One litre is equivalent to this cubeEach side is 10 cm1 litre water = 1 kilogram water The litre is a metric system unit of volume equal to 1 cubic decimetre , to 1,000 cubic centimetres , and to 1/1,000 cubic metre...

(1 dm3) for volumes of liquid
• The gram
Gram
The gram is a metric system unit of mass....

for mass

Although the law defined the length of the metre, there was no practical way of accurately measuring the metre (and hence the are) until 1799 when the first standard metre was manufactured and adopted.

The standard metre remained in the custody of successive French governments until 1875 when, under the Convention of the Metre, its supervision passed into international control under the auspices of the General Conference on Weights and Measures
General Conference on Weights and Measures
The General Conference on Weights and Measures is the English name of the Conférence générale des poids et mesures . It is one of the three organizations established to maintain the International System of Units under the terms of the Convention du Mètre of 1875...

(GCPM). At the first meeting of the GCPM in 1889 when a new standard metre, manufactured by Johnson Matthey & Co of London was adopted, the are and hectare were automatically redefined.

In 1960, when the metric system was updated as the International System of Units
International System of Units
The International System of Units is the modern form of the metric system and is generally a system of units of measurement devised around seven base units and the convenience of the number ten. The older metric system included several groups 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 current (2006) definition of the SI, but classifies the hectare as a "Non-SI unit accepted for use with the International System of Units"

In 1972, the European Economic Community
European Economic Community
The European Economic Community The European Economic Community (EEC) The European Economic Community (EEC) (also known as the Common Market in the English-speaking world, renamed the European Community (EC) in 1993The information in this article primarily covers the EEC's time as an independent...

(EEC) passed directive 71/354/EEC
, which catalogued the units of measure that might be used within the community. The units that were catalogued replicated the recommendations of the GCPM, supplemented by a few other units including the are (and implicitly the hectare) whose use was limited to the measurement of land.

## The units

The names centiare, decare and hectare are derived by adding the standard metric prefixes
SI prefix
The International System of Units specifies a set of unit prefixes known as SI prefixes or metric prefixes. An SI prefix is a name that precedes a basic unit of measure to indicate a decadic multiple or fraction of the unit. Each prefix has a unique symbol that is prepended to the unit symbol...

to the original base unit of area
Area
Area is a quantity that expresses the extent of a two-dimensional surface or shape in the plane. Area can be understood as the amount of material with a given thickness that would be necessary to fashion a model of the shape, or the amount of paint necessary to cover the surface with a single coat...

, the are.

### Are

The are (icon or ˈ; symbol a) is a unit of area
Area
Area is a quantity that expresses the extent of a two-dimensional surface or shape in the plane. Area can be understood as the amount of material with a given thickness that would be necessary to fashion a model of the shape, or the amount of paint necessary to cover the surface with a single coat...

, equal to 100 square metre
Square metre
The square metre or square meter is the SI derived unit of area, with symbol m2 . It is defined as the area of a square whose sides measure exactly one metre...

s (10 m × 10 m), used for measuring land area. It was defined by older forms of the metric system
Metric system
The metric system is an international decimalised system of measurement. France was first to adopt a metric system, in 1799, and a metric system is now the official system of measurement, used in almost every country in the world...

, but is now outside of the modern International System
Si
Si, si, or SI may refer to :- Measurement, mathematics and science :* International System of Units , the modern international standard version of the metric system...

(SI).

It is commonly used to measure real estate, in particular in Indonesia
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...

and in French
French language
French is a Romance language spoken as a first language in France, the Romandy region in Switzerland, Wallonia and Brussels in Belgium, Monaco, the regions of Quebec and Acadia in Canada, and by various communities elsewhere. Second-language speakers of French are distributed throughout many parts...

-, Portuguese
Portuguese language
Portuguese is a Romance language that arose in the medieval Kingdom of Galicia, nowadays Galicia and Northern Portugal. The southern part of the Kingdom of Galicia became independent as the County of Portugal in 1095...

-, Slovakian
Slovak language
Slovak , is an Indo-European language that belongs to the West Slavic languages .Slovak is the official language of Slovakia, where it is spoken by 5 million people...

-, Czech
Czech language
Czech is a West Slavic language with about 12 million native speakers; it is the majority language in the Czech Republic and spoken by Czechs worldwide. The language was known as Bohemian in English until the late 19th century...

-, Polish
Polish language
Polish is a language of the Lechitic subgroup of West Slavic languages, used throughout Poland and by Polish minorities in other countries...

-, Dutch
Dutch language
Dutch is a West Germanic language and the native language of the majority of the population of the Netherlands, Belgium, and Suriname, the three member states of the Dutch Language Union. Most speakers live in the European Union, where it is a first language for about 23 million and a second...

-, and German
German language
German is a West Germanic language, related to and classified alongside English and Dutch. With an estimated 90 – 98 million native speakers, German is one of the world's major languages and is the most widely-spoken first language in the European Union....

-speaking countries.

In Russia and other former Soviet Union
Soviet Union
The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....

states, the "sotka" (сотка 'hundredth') is identical to the are. It is used to describe the size of suburban dacha
Dacha
Dacha is a Russian word for seasonal or year-round second homes often located in the exurbs of Soviet and post-Soviet cities. Cottages or shacks serving as family's main or only home are not considered dachas, although many purpose-built dachas are recently being converted for year-round residence...

or allotment garden plots or small city parks where the hectare would be too large.

### Decare

The decare (symbol daa) is derived from deka, the prefix for 10 and are
ARE
Are, ARE or Åre may refer to: United Arab Emirates using ISO 3166-1 alpha-3 country code*The second-person singular and plural forms of the verb "to be", copula of the English language...

, and is equal to 10 ares or 1000 square metre
Square metre
The square metre or square meter is the SI derived unit of area, with symbol m2 . It is defined as the area of a square whose sides measure exactly one metre...

s. It is used in Norway and in the former Ottoman
Ottoman Empire
The Ottoman EmpireIt was usually referred to as the "Ottoman Empire", the "Turkish Empire", the "Ottoman Caliphate" or more commonly "Turkey" by its contemporaries...

areas of the Middle East and the Balkans as a measure of land area. In the formerly Ottoman area, instead of the name 'decare', the names of traditional land measures are usually used, redefined as one decare:
• Stremma
Stremma
The stremma is a Greek unit of land area, equal to 1,000 square metres, also called the 'royal' stremma. The name comes from a root meaning 'to turn', presumably referring to the amount of land that can be plowed/turned in a day....

in Greece
Greece
Greece , officially the Hellenic Republic , and historically Hellas or the Republic of Greece in English, is a country in southeastern Europe....

• Dunam
Dunam
A dunam or dönüm, dunum, donum, dynym, dulum was a non-SI unit of land area used in the Ottoman Empire and representing the amount of land that can be plowed in a day; its value varied from 900–2500 m²...

, dunum, donum, or dönüm in Israel
Israel
The State of Israel is a parliamentary republic located in the Middle East, along the eastern shore of the Mediterranean Sea...

, Jordan
Jordan
Jordan , officially the Hashemite Kingdom of Jordan , Al-Mamlaka al-Urduniyya al-Hashemiyya) is a kingdom on the East Bank of the River Jordan. The country borders Saudi Arabia to the east and south-east, Iraq to the north-east, Syria to the north and the West Bank and Israel to the west, sharing...

, Lebanon
Lebanon
Lebanon , officially the Republic of LebanonRepublic of Lebanon is the most common term used by Lebanese government agencies. The term Lebanese Republic, a literal translation of the official Arabic and French names that is not used in today's world. Arabic is the most common language spoken among...

, Syria and Turkey
Turkey
Turkey , known officially as the Republic of Turkey , is a Eurasian country located in Western Asia and in East Thrace in Southeastern Europe...

### Hectare

The hectare (icon or ˈ; symbol ha) is widely used throughout the world and is the legal unit of measure in domains concerned with land ownership, planning, and management
Land management
Land management is the process of managing the use and development of land resources. Land resources are used for a variety of purposes which may include organic agriculture, reforestation, water resource management and eco-tourism projects.-See also:*Sustainable land management*Acreage...

, including law (land deeds
Deed
A deed is any legal instrument in writing which passes, or affirms or confirms something which passes, an interest, right, or property and that is signed, attested, delivered, and in some jurisdictions sealed...

), agriculture
Agriculture
Agriculture is the cultivation of animals, plants, fungi and other life forms for food, fiber, and other products used to sustain life. Agriculture was the key implement in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that nurtured the...

, forestry
Forestry
Forestry is the interdisciplinary profession embracing the science, art, and craft of creating, managing, using, and conserving forests and associated resources in a sustainable manner to meet desired goals, needs, and values for human benefit. Forestry is practiced in plantations and natural stands...

, and town planning throughout the European Union
European Union
The European Union is an economic and political union of 27 independent member states which are located primarily in Europe. The EU traces its origins from the European Coal and Steel Community and the European Economic Community , formed by six countries in 1958...

. The United States, Burma and to some extent Canada instead use the acre
Acre
The acre is a unit of area in a number of different systems, including the imperial and U.S. customary systems. The most commonly used acres today are the international acre and, in the United States, the survey acre. The most common use of the acre is to measure tracts of land.The acre is related...

..

Some countries that underwent a general conversion from traditional measurements to metric
Metric system
The metric system is an international decimalised system of measurement. France was first to adopt a metric system, in 1799, and a metric system is now the official system of measurement, used in almost every country in the world...

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.

In many countries, metrication redefined or clarified existing measures in terms of metric units. (cf. :Category:Metricated units) The following legacy units of area have been redefined as being equal to one hectare:
• Jerib
Jerib
The jerib or djerib is a traditional unit of land measurement in the Middle East and southwestern Asia. It is a unit of area used to measure land holdings in much the way that an acre or hectare are. Like most traditional units of measure, the jerib originally varied substantially from one...

in Iran
• Djerib
Jerib
The jerib or djerib is a traditional unit of land measurement in the Middle East and southwestern Asia. It is a unit of area used to measure land holdings in much the way that an acre or hectare are. Like most traditional units of measure, the jerib originally varied substantially from one...

in Turkey
• Gong qǐng in mainland China
• Manzana
Manzana (unit)
A manzana is a Central American unit of area:* 1 Manzana = 1.68 acres* 1 Manzana = 10,000 sq. Varas-External links:* http://www.sizes.com/units/manzana.htm* http://www.unc.edu/~rowlett/units/dictM.html#manzana...

in Argentina
• Bunder
Bunder
A bunder is a unit of area in the Low Countries .In the Netherlands it was frequently used in the Achterhoek, Twente and some parts of Drenthe to estimate areas of land, in particular in agriculture...

in The Netherlands (until 1937)

## Conversions

 Metric and Imperial/US Customary Comparisons Units Symbol Metric Equivalents Imperial/US Customary Equivalents centiare ca 1 m2 0.01 a 1.19599 sq ydSquare yardThe square yard is an imperial/US customary unit of area, formerly used in most of the English-speaking world but now generally replaced by the square metre outside of the U.S., Canada and the U.K. It is defined as the area of a square with sides of one yard in length... are a 100 ca 100 m2 0.01 ha 3.95369 perches decare daa 10 a 1,000 m2 0.1 ha 0.98842 roods hectare ha 100 a 10,000 m2 0.01 km2 2.47105 acres square kilometre km2 100 ha 1,000,000 m2 0.38610 sq miSquare mileThe square mile is an imperial and US unit of measure for an area equal to the area of a square of one statute mile. It should not be confused with miles square, which refers to the number of miles on each side squared...

The most commonly used units are in bold.

One hectare is also equivalent to:
• 2.4710439 U.S. survey acre
Acre
The acre is a unit of area in a number of different systems, including the imperial and U.S. customary systems. The most commonly used acres today are the international acre and, in the United States, the survey acre. The most common use of the acre is to measure tracts of land.The acre is related...

s
• 15 mǔ or 0.15 qǐng
• 10 dunam
Dunam
A dunam or dönüm, dunum, donum, dynym, dulum was a non-SI unit of land area used in the Ottoman Empire and representing the amount of land that can be plowed in a day; its value varied from 900–2500 m²...

or dönüm (Middle East)
• 10 stremma
Stremma
The stremma is a Greek unit of land area, equal to 1,000 square metres, also called the 'royal' stremma. The name comes from a root meaning 'to turn', presumably referring to the amount of land that can be plowed/turned in a day....

ta (Greece)
• 6.25 rai (Thai)
• ≈ 1.008 chō (Japanese)

## Visualising a hectare

Visitors to London can visualize a hectare by visiting Trafalgar Square
Trafalgar Square
Trafalgar Square is a public space and tourist attraction in central London, England, United Kingdom. At its centre is Nelson's Column, which is guarded by four lion statues at its base. There are a number of statues and sculptures in the square, with one plinth displaying changing pieces of...

.

### International rugby field

 style="border: 1px solid #FFFFFF;" On an international rugby unionRugby unionRugby union, often simply referred to as rugby, is a full contact team sport which originated in England in the early 19th century. One of the two codes of rugby football, it is based on running with the ball in hand... field the goal lines are up to 100 metres apart. Behind the goal line is the in-goal area (which is also a playing area). This area extends between 10 and 22 metres behind the goal line, giving a maximum length of 144 metres for the playing area. The maximum width of the pitch is 70 metres, giving a maximum playing area of 10,080 square metres or 1.008 hectares.

### Statue of Liberty

 style="border: 1px solid #FFFFFF;" 40°41′21"N 74°2′40"W The Statue of LibertyStatue of LibertyThe Statue of Liberty is a colossal neoclassical sculpture on Liberty Island in New York Harbor, designed by Frédéric Bartholdi and dedicated on October 28, 1886..., a gift from the French people to the American people dedicated on 28 October 1886 to commemorate the hundredth anniversary of the French and American Revolutions, is located on Liberty IslandLiberty IslandLiberty Island is a small uninhabited island in New York Harbor in the United States, best known as the location of the Statue of Liberty. Though so called since the turn of the century, the name did not become official until 1956. In 1937, by proclamation 2250, President Franklin D... at the entrance to New York HarborNew York HarborNew York Harbor refers to the waterways of the estuary near the mouth of the Hudson River that empty into New York Bay. It is one of the largest natural harbors in the world. Although the U.S. Board of Geographic Names does not use the term, New York Harbor has important historical, governmental,.... Its base is built on eighteenth-century fortifications. The distance between the apexApex (geometry)In geometry, an apex is the vertex which is in some sense the highest of the figure to which it belongs.*In an isosceles triangle, the apex is the vertex where the two sides of equal length meet, opposite the unequal third side.... of the bastionBastionA bastion, or a bulwark, is a structure projecting outward from the main enclosure of a fortification, situated in both corners of a straight wall , facilitating active defence against assaulting troops...s in the front of the base to those at the back (where the entrance to the statue is located) is approximately 100 m while the distance between the apexes of the left-hand and right-hand bastions is a little under 100 m. Thus, if a square were to enscribe the bastions, it would have sides of approximately 100 m, giving it an area of one hectare.

### Interior of all-weather athletics track

 style="border: 1px solid #FFFFFF;" Athletics tracks are found in almost every country of the world. Although many tracks consist of markings on a field of suitable size, where funds permit, specialist all-weather tracks have a rubberized artificial running surface with a grass interior (as shown in the picture and diagram). The perimeter of the inside kerb of the track is a little under 400 metres, as the actual length of the track is measured 300 mm from the inside kerb. The IAAF specifications state that the radius of the kerb is 36.5 m, from which it can be calculated that the area inside the kerb is 1.035 ha.

• 1 E+4 m² for further comparisons
• Conversion of units
Conversion of units
Conversion of units is the conversion between different units of measurement for the same quantity, typically through multiplicative conversion factors.- Process :...

• Hecto-
• Hectometre
Hectometre
A hectometre is a somewhat uncommonly used unit of length in the metric system, equal to one hundred metres. It derives from the Greek word "ekato", meaning "hundred". A regulation football or soccer field is approximately 1 hectometre in length.*For area the square hectometre is a common unit...

• Order of magnitude
Order of magnitude
An order of magnitude is the class of scale or magnitude of any amount, where each class contains values of a fixed ratio to the class preceding it. In its most common usage, the amount being scaled is 10 and the scale is the exponent being applied to this amount...