Square kilometre

{{Infobox unit | name = square kilometre | image = Comparison of units of area.png | caption = The square kilometre (red square) compared to other areas, including a square mile (the entire yellow square) | standard = SI units | quantity = area | symbol = km2 | units1 = SI units | inunits1 = {{ubl|{{val|1000000|u=m2}}|{{val|100|u=ha}}}} | units2 = Imperial/US | inunits2 = {{ubl|{{val|0.3861|u=mi2}}||{{val|247.1|u=acres}}}} }}

The '''square kilometre''' ('''square kilometer''' in American spelling; symbol: '''km2''') is a multiple of the square metre, the SI unit of area or surface area. In the SI unit of area (m2), 1 km2 is equal to 1M(m2).

1 km2 is equal to: * 1,000,000 square metres (m2) * 100 hectares (ha) It is also approximately equal to: * 0.3861 square miles {{#tag:ref|There are 0.386102159 international square miles in a square kilometer while there are 0.386100614 US Survey square miles in the same measure. This is because the US Survey measures are very slightly larger than the international measures.<ref name="unitconversion">{{cite web |url=http://www.unitconversion.org/unit_converter/area-s.html |title=UnitConversion.org Area Converter|year=2009 |work=web page |publisher=UnitConversion.org |access-date=4 July 2012}}</ref>}} * 247.1 acres {{#tag:ref|There are 247.105381467 international acres in a square kilometre while there are only 247.104393047 of the very slightly larger US Survey acres.<ref name="unitconversion"/>}}

Conversely: *1 m2 = 0.000001 (10−6) km2 *1 hectare = 0.01 (10−2) km2 *1 square mile = {{val|2.5899|u=km2}} {{#tag:ref|An International square mile equals {{val|2.58998811|u=km2}} while the slightly larger US Survey square mile equals {{val|2.58999847|u=km2}}.<ref name="unitconversion"/>}} *1 acre = about {{val|0.004047|u=km2}} {{#tag:ref|1 acre (International) = {{val|0.004046856|u=km2}} while 1 acre (US Survey) = {{val|0.004046873|u=km2}} <ref name="unitconversion"/>}}

The symbol "km2" means (km)2, square kilometre and not k(m2), kilo–square metre. For example, 3 km2 is equal to {{gaps|3|×|(1,000|m)2}} = 3,000,000 m2, not 3,000 m2.

==Examples of areas of 1 square kilometre== ===Topographical map grids=== thumb|300px|Part of an Ordnance Survey map, published 1952. The grid lines are at one-kilometre intervals, giving each square an area of one square kilometre. The map shows that the area of the island is about two square kilometres.Topographical map grids are worked out in metres, with the grid lines being 1,000 metres apart. * 1:100,000 maps are divided into squares representing 1 km2, each square on the map being one square centimetre in area and representing 1 km2 on the surface of the Earth. * For 1:50,000 maps, the grid lines are 2 cm apart. Each square on the map is 2 cm by 2 cm (4 cm2) and represents 1 km2 on the surface of the Earth. * For 1:25,000 maps, the grid lines are 4 cm apart. Each square on the map is 4 cm by 4 cm (16 cm2) and represents 1 km2 on the surface of the Earth. In each case, the grid lines enclose one square kilometre.

===Medieval city centres===

[[File:Dimensions of the old city of Delft.svg|260px|right|thumb|Map of Delft, Netherlands, dated 1659. The walls enclosed an area of about 1 square kilometre.]] The area enclosed by the walls of many European medieval cities were about one square kilometre. These walls are often either still standing or the route they followed is still clearly visible, such as in Brussels, where the wall has been replaced by a ring road, or in Frankfurt, where the wall has been replaced by gardens. The approximate area of the old walled cities can often be worked out by fitting the course of the wall to a rectangle or an oval (ellipse). Examples include: *Delft, Netherlands (See map alongside) {{coord|52|0|54|N|4|21|34|E}} :The walled city of Delft was approximately rectangular. ::The approximate length of rectangle was about {{convert|1.30|km|mi}}.<ref name=GE>Measurements taken from Google Earth</ref> ::The approximate width of the rectangle was about {{convert|0.75|km|mi}}.<ref name=GE/> ::A perfect rectangle with these measurements has an area of 1.30×0.75 = 0.9 km2

*Lucca (Italy) {{coord|43|50|38|N|10|30|2|E}} :The medieval city is roughly rectangular with rounded north-east and north-west corners. ::The maximum distance from east to west is {{convert|1.36|km|mi}}.<ref name=GE/> ::The maximum distance from north to south is {{convert|0.80|km|mi}}.<ref name=GE/> ::A perfect rectangle of these dimensions would be 1.36×0.80 = 1.088 km2.

*Bruges (Belgium) {{coord|51|12|39|N|3|13|28|E}} :The medieval city of Bruges, a major centre in Flanders, was roughly oval or elliptical in shape with the longer or semi-major axis running north and south. ::The maximum distance from north to south (semi-major axis) is {{convert|2.53|km|mi}}.<ref name=GE/> ::The maximum distance from east to west (semi-minor axis) is {{convert|1.81|km|mi}}.<ref name=GE/> ::A perfect ellipse of these dimensions would be 2.53 × 1.81 × (π/4) = 3.597 km2.

*Chester United Kingdom {{coord|53|12|1|N|2|52|45|W}} :Chester is one of the smaller English cities that has a near-intact city wall.<ref>{{cite web |url = http://www.chesterwalls.info/chestermap.html |title = Chester: A Virtual Stroll around the Walls |first = Steve |last = Howe |access-date = 7 October 2012}}</ref> ::The distance from Northgate to Watergate is about 855 metres.<ref name=GE/> ::The distance from Eastgate to Westgate is about 589 metres.<ref name=GE/> ::A perfect rectangle of these dimensions would be (855/1000) × (589/1000) = 0.504 km2.

===Parks=== Parks come in all sizes; a few are almost exactly one square kilometre in area. Here are some examples: * Riverside Country Park, UK.<ref>{{cite web |url=http://www.medway.gov.uk/environmentandplanning/countrysidesites/riversidecountrypark.aspx |title=Medway Council Riverside Country Park |year=2012 |work=web page |publisher=Medway Council |access-date=9 June 2012 |url-status=dead |archive-url=https://web.archive.org/web/20120419013431/http://www.medway.gov.uk/environmentandplanning/countrysidesites/riversidecountrypark.aspx |archive-date=19 April 2012 }}</ref> * Brierley Forest Park, UK.<ref>{{cite web |url=http://www.ashfield-dc.gov.uk/ccm/navigation/leisure-and-culture/tourism-and-heritage/country-parks-and-trails/brierley-forest-park-visitor-centre-/;jsessionid=F08C5878102681F9392CAAFF7EAB8DF7 |title=Ashfield Brierley Forest Park |year=2012 |work=web page |publisher=Ashfield District Council |access-date=9 June 2012 |url-status=dead |archive-url=https://web.archive.org/web/20121108034331/http://www.ashfield-dc.gov.uk/ccm/navigation/leisure-and-culture/tourism-and-heritage/country-parks-and-trails/brierley-forest-park-visitor-centre-/;jsessionid=F08C5878102681F9392CAAFF7EAB8DF7 |archive-date=8 November 2012 }}</ref> * Rio de Los Angeles State Park, California, US <ref>{{cite web |url=http://www.parks.ca.gov/?page_id=22277 |title=California Department of Parks and Recreation Rio de Los Angeles State Park |year=2012 |work=web page |publisher=State of California|access-date=9 June 2012}}</ref> * Jones County Central Park, Iowa, US.<ref>{{cite web |url=http://www.jonescountytourism.com/parks/centralpark.html |title=Parks & Recreation Central Park, Center Junction, Iowa |work=web page |publisher=Jones County Tourism Association |access-date=9 June 2012}}</ref> * Kiest Park, Dallas, Texas, US <ref>{{cite web |url=http://friendsofoakcliffparks.org/kiesthistory.htm |title=A History of Kiest Park |year=2010 |work=web page |publisher=Friends of Oak Cliff Parks |access-date=9 June 2012 |url-status=dead |archive-url=https://web.archive.org/web/20120605053208/http://friendsofoakcliffparks.org/kiesthistory.htm |archive-date=5 June 2012 }}</ref> * Hole-in-the-Wall Park & Campground, Grand Manan Island, Bay of Fundy, New Brunswick, Canada <ref>{{cite web |url=http://www.grandmanancamping.com/maps.php |title=Hole-in-the-Wall Park & Campground |year=2012 |work=web page |publisher=Hole-in-the-Wall Park & Campground|access-date=9 June 2012}}</ref> * Downing Provincial Park, British Columbia, Canada <ref>{{cite web |url=http://www.env.gov.bc.ca/bcparks/explore/parkpgs/downing/ |title=BC Parks Downing Provincial Park |work=web page |publisher=British Columbia Ministry of Environment |access-date=9 June 2012}}</ref> * Citadel Park, Poznan, Poland <ref>{{cite web |url=http://culture.poland.travel/poznan/citadel-park |title=Citadel Park |work=web page |publisher=Poland Travel |access-date=9 June 2012}}</ref> * Sydney Olympic Park, Sydney, Australia, contains 6.63 square kilometres of wetlands and waterways.<ref>{{cite web |url=http://www.sopa.nsw.gov.au/media/pdfs/publications/fact_sheets/parklands_fact_sheet |title=Sydney Olympic Park Parklands Fact Sheet |work=web page |publisher=Sydney Olympic Park Authority |access-date=9 June 2012}}</ref>

===Golf courses=== Using the figures published by golf course architects Crafter and Mogford, a course should have a fairway width of 120 metres and 40 metres clear beyond the hole. Assuming a {{convert|6000|m|yd|adj=on}} 18-hole course, an area of 80 hectares (0.8 square kilometre) needs to be allocated for the course itself.<ref>{{cite web |url = http://www.golfstrategies.com.au/graphics/articles/FS.6.Safety.pdf |title = Golf Course Safety |publisher = Crafter + Mogford, golf course architects |access-date = 5 October 2012}}</ref><ref group=Note>Assume that each hole requires (6000÷18 + 40) = 373 metres in length. The area needed is (18 × 373 × 120 ÷ 10,000) = 80.64 ha (1 hectare = 10,000 square metres).</ref> Examples of golf courses that are about one square kilometre include: * Manchester Golf Club, UK <ref name="Manchester Golf Club Ltd">{{cite web |url=http://www.mangc.co.uk/visitors.htm |title=Visitor Information [Manchester Golf Club] |work=web page |publisher=Manchester Golf Club Ltd |access-date=11 June 2012 |url-status=dead |archive-url=https://web.archive.org/web/20120525133739/http://www.mangc.co.uk/visitors.htm |archive-date=25 May 2012 }}</ref> * Northop Country Park, Wales, UK <ref name="Manchester Golf Club Ltd"/> * The Trophy Club, Lebanon, Indiana, US <ref>{{cite web |url=http://thetrophyclubgolf.com/ |title=Welcome to the Trophy Club |work=web page |publisher=The Trophy Club |access-date=11 June 2012}}</ref> * Qingdao International Country Golf Course, Qingdao, Shandong, China * Arabian Ranches Golf Club, Dubai <ref>{{cite web |url=http://www.7daysindubai.com/sport-and-leisure/golf-courses/arabian-ranches-golf-club/business-15488895-detail/business.html |archive-url=https://web.archive.org/web/20120908003417/http://www.7daysindubai.com/sport-and-leisure/golf-courses/arabian-ranches-golf-club/business-15488895-detail/business.html |archive-date=2012-09-08 |title=Arabian Ranches Golf Club |work=7 Days in Dubai |publisher= Catchpole Communications FZ-LLC, Al Sidra Media LLC. |access-date=1 April 2018}}</ref> * Sharm el Sheikh Golf Courses: Sharm el Sheikh, South Sinai, Egypt <ref>{{cite web |url=http://www.sharm-el-sheikh.world-guides.com/sharm_el_sheikh_golf.html|title=Sharm el Sheikh Golf Courses: Sharm el Sheikh, South Sinai, Egypt |work=web page |publisher=TravelSmart Ltd: World Guides |access-date=11 June 2012}}</ref> * Belmont Golf Club, Lake Macquarie, NSW, Australia <ref>{{cite web |url=http://www.belmontgolf.com.au/layouts/mp_standard/Template.aspx?page=History|title=Belmont Golf Club, Lake Macquarie, History |work=web page |publisher=Belmont Golf Club |access-date=11 June 2012}}</ref>

===Other areas of one square kilometre or thereabouts=== * The Old City of Jerusalem is almost 1 square kilometre in area.<ref>{{cite web |url=https://www.jewishvirtuallibrary.org/jsource/vie/Jerusalem2.html |title=Jerusalem - The Old City |year=2012 |work=web page |publisher=The American-Israeli Cooperative Enterprise |access-date=6 July 2012}} Actually, about 89 hectares.</ref> *Milton Science Park, Oxfordshire, UK.<ref>{{cite web |url=http://www.sciencevale.com/milton/ |title=Science Vale UK |work=web page |publisher= Abbey House|access-date=7 July 2012}} </ref> * Mielec Industrial Park, Mielec, Poland <ref>{{cite web |url=http://www.paiz.gov.pl/investment_support/industrial_and_technology_parks/mielec |title=Invest in Poland |work=web page |publisher=Polish information and foreign investment agency |access-date=7 July 2012}}</ref> * The Guildford Campus of Guildford Grammar School, South Guildford, Western Australia<ref>{{cite web |url=http://www.waterhall.com.au/lifestyle/history/guildford |archive-url=https://web.archive.org/web/20130410123141/http://www.waterhall.com.au/lifestyle/history/guildford |archive-date=10 April 2013 |title=Guildford Grammar School|work=waterhall.com.au |access-date=2 April 2018 }}</ref> * Sardar Vallabhbhai National Institute of Technology (SVNIT), Surat, India <ref>{{cite web |url=http://www.svnit.ac.in/conferences/fmfp2012/about%20us.html |title=39th National Conference on Fluid Mechanics and Fluid Power |work=web page |publisher=Department of Mechanical Engineering, Sardar Vallabhbhai National Institute of Technology (SVNIT) |access-date=7 July 2012 |url-status=dead |archive-url=https://web.archive.org/web/20120719081320/http://svnit.ac.in/conferences/fmfp2012/about%20us.html |archive-date=19 July 2012 }}</ref> * Île aux Cerfs, near the east coast of Mauritius.<ref>{{cite web |url=http://www.amity.edu/mauritius/MauritiusAttraction.asp |title=MauritiusAttraction |date=2011 |website=Amity Institute of Higher Education, Mauritius |publisher=Amity Institute of Higher Education |access-date=27 June 2013 |url-status=dead |archive-url=https://web.archive.org/web/20131012085638/http://www.amity.edu/Mauritius/MauritiusAttraction.asp |archive-date=12 October 2013 }}</ref> *Peng Chau Island, Hong Kong<ref>{{cite web|url=http://e-cgo.org.hk/travel/en/trip-detail?id=10|title=Peng Chau<Leisure Line - Barrier-Free Information Website - Hong Kong Federation of Handicapped Youth|website=e-cgo.org.hk}}</ref>

==See also== *Conversion of units *SI prefix for the precise meaning of the prefix "k" *Square Kilometre Array, a proposed radio telescope in both South Africa and Australia, which is intended to have a collecting area of approximately 1 km2

==Notes== {{Reflist|group = Note}}

==References== {{reflist}}

Category:Units of area Category:SI derived units