Visualization of one hectare
|Unit system||Non-SI unit accepted for use with SI|
|In SI base units:||1 ha = 104 m2|
The hectare (/
In 1795, when the metric system was introduced, the "are" was defined as 100 square metres and the hectare ("hecto-" + "are") was thus 100 "ares" or 1⁄100 km2. 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 units, mentioned in Section 4.1 of the SI Brochure as a unit whose use is "expected to continue indefinitely".
|1 ca||1 m2|
|1 a||100 m2|
|1 ha||10,000 m2|
|100 ha||1,000,000 m2|
|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 metre for length
- The are (100 m2) for area [of land]
- The stère (1 m3) for volume of stacked firewood
- 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 ( ) 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 (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 CGPM, supplemented by a few other units including the are (and implicitly the hectare) whose use was limited to the measurement of land.
Many UK farmers, especially older ones, still use the acre for everyday calculations, and convert to hectares only for official (especially European Union) paperwork. Farm fields can have very long histories which are resistant to change, with names such as "the six acre field" stretching back hundreds of years and across generations of family farmers. Some younger agricultural workers are now beginning to think in hectares as their "first language", though this is more typical of professional consultants and managers than of traditional farming and land-owning families, and in some circles may be viewed as a social class indicator.
The names centiare, deciare, decare and hectare are derived by adding the standard metric prefixes to the original base unit of area, the are.
The centiare is one square metre.
The deciare is ten square metres.
The are (// or //) 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). It is still commonly used in colloquial speech to measure real estate, in particular in Indonesia, India, and in various European countries.
In Russian and 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.
The decare (/
The hectare (/
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".
|Metric and imperial/US customary comparisons|
|Unit||Symbol||Metric equivalents||Imperial/US customary equivalents|
|centiare||ca||1 m2||0.01 a||1.19599 sq yd|
|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||2.471 acres|
|square kilometre||km2||100 ha||1,000,000 m2||0.38610 sq mi|
The most commonly used units are in bold.
One hectare is also equivalent to:
Visualising a hectare
International rugby pitch
On an international rugby union 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
The distance between the apex of the bastions 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
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- 2.4710439 U.S. survey acres or 2.4710538 international acres
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