The kilometre ( SI symbol: km; or ), spelt kilometer in American English, is a unit of length in the International System of Units (SI), equal to one thousand metres (kilo- being the SI prefix for ). It is now the measurement unit used for ex ...
( International spelling
as used by the International Bureau of Weights and Measures
) or square kilometer (American spelling), symbol km2
, is a multiple of the
The square metre ( international spelling as used by the International Bureau of Weights and Measures) or square meter ( American spelling) is the unit of area in the International System of Units (SI) with symbol m2. It is the area of a squ ...
, the SI
Unit may refer to:
Arts and entertainment
* UNIT, a fictional military organization in the science fiction television series ''Doctor Who''
* Unit of action, a discrete piece of action (or beat) in a theatrical presentation
* ''Unit'' (a ...
The surface area of a solid object is a measure of the total area that the surface of the object occupies. The mathematical definition of surface area in the presence of curved surfaces is considerably more involved than the definition of ar ...
is equal to:
* 1,000,000 square metres (m2
The hectare (; SI symbol: ha) is a non-SI metric unit of area equal to a square with 100-metre sides (1 hm2), or 10,000 m2, and is primarily used in the measurement of land. There are 100 hectares in one square kilometre. An acre is a ...
It is also approximately equal to:
The square mile (abbreviated as sq mi and sometimes as mi2)Rowlett, Russ (September 1, 2004) University of North Carolina at Chapel Hill. Retrieved February 22, 2012. is an imperial and US unit of measure for area. One square mile is an ...
* 247.1 acre
= 0.000001 (10−6
*1 hectare = 0.01 (10−2
*1 square mile =
*1 acre = about
The symbol "km2
" means (km)2
, square kilometre or kilometre squared and not k(m2
), kilo–square metre. For example, 3 km2
is equal to = 3,000,000 m2
, not 3,000 m2
Examples of areas of 1 square kilometre
Topographical Map grids
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
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 (french: Bruxelles or ; nl, Brussel ), officially the Brussels-Capital Region (All text and all but one graphic show the English name as Brussels-Capital Region.) (french: link=no, Région de Bruxelles-Capitale; nl, link=no, Bruss ...
, where the wall has been replaced by a ring road, or in
Frankfurt, officially Frankfurt am Main (; Hessian: , " Frank ford on the Main"), is the most populous city in the German state of Hesse. Its 791,000 inhabitants as of 2022 make it the fifth-most populous city in Germany. Located on its n ...
, 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
, Netherlands (See map alongside)
:The walled city of Delft was approximately rectangular.
::The approximate length of rectangle was about .
[Measurements taken from ] Google Earth
Google Earth is a computer program that renders a 3D computer graphics, 3D representation of Earth based primarily on satellite imagery. The program maps the Earth by superimposition, superimposing satellite images, aerial photography, and geog ...
::The approximate width of the rectangle was about .
::A perfect rectangle with these measurements has an area of 1.30×0.75 = 0.9 km2
* Lucca (Italy)
:The medieval city is roughly rectangular with rounded north-east and north-west corners.
::The maximum distance from east to west is .] [
::The maximum distance from north to south is .] [
::A perfect rectangle of these dimensions would be 1.36×0.80 = 1.088 km2.
Bruges ( , nl, Brugge ) is the capital and largest city of the province of West Flanders in the Flemish Region of Belgium, in the northwest of the country, and the sixth-largest city of the country by population.
The area of the whole city ... (Belgium)
:The medieval city of Bruges, a major centre in Flanders
Flanders (, ; Dutch language, Dutch: ''Vlaanderen'' ) is the Dutch language, Flemish-speaking northern portion of Belgium and one of the communities, regions and language areas of Belgium. However, there are several overlapping definitions, in ..., was roughly oval or elliptical
Elliptical may mean:
* having the shape of an ellipse, or more broadly, any oval shape
** in botany, having an elliptic leaf shape
** of aircraft wings, having an elliptical planform
* characterised by ellipsis (the omission of words), or by conc ... in shape with the longer or semi-major axis
In geometry, the major axis of an ellipse is its longest diameter: a line segment that runs through the center and both foci, with ends at the two most widely separated points of the perimeter. The semi-major axis (major semiaxis) is the long ... running north and south.
::The maximum distance from north to south (semi-major axis) is . [
::The maximum distance from east to west (semi-minor axis) is .] [
::A perfect ellipse of these dimensions would be 2.53 × 1.81 × ( π/4) = 3.597 km2.
Chester is a cathedral city and the county town of Cheshire, England. It is located on the River Dee, close to the English–Welsh border. With a population of 79,645 in 2011,"2011 Census results: People and Population Profile: Chester Local ... United Kingdom
:Chester is one of the smaller English cities that has a near-intact city wall.
::The distance from Northgate to Watergate
The Watergate scandal was a major political scandal in the United States involving the administration of President Richard Nixon from 1972 to 1974 that led to Nixon's resignation. The scandal stemmed from the Nixon administration's continual ... is about 855 metres. [
::The distance from Eastgate to Westgate is about 589 metres.] [
::A perfect rectangle of these dimensions would be (855/1000) × (589/1000) = 0.504 km2.
Parks come in all sizes; a few are almost exactly one square kilometre in area. Here are some examples:
* Riverside Country Park, UK.
* Brierley Forest Park, UK.
* Rio de Los Angeles State Park, California, USA
* Jones County Central Park, Iowa, USA.
* Kiest Park, Dallas, Texas, USA
* Hole-in-the-Wall Park & Campground, Grand Manan Island, Bay of Fundy, New Brunswick, Canada
* Downing Provincial Park, British Columbia, Canada
* Citadel Park, Poznan, Poland
* Sydney Olympic Park, Sydney, Australia, contains 6.63 square kilometres of wetlands and waterways.
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 18-hole course, an area of 80 hectares (0.8 square kilometre) needs to be allocated for the course itself.
[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).] Examples of golf courses that are about one square kilometre include:
* Manchester Golf Club, UK
* Northop Country Park, Wales, UK
* The Trophy Club, Lebanon, Indiana, US
* Qingdao International Country Golf Course, Qingdao, Shandong, China
* Arabian Ranches Golf Club, Dubai
* Sharm el Sheikh Golf Courses: Sharm el Sheikh, South Sinai, Egypt
* Belmont Golf Club, Lake Macquarie, NSW, Australia
Other areas of one square kilometre or thereabouts
* The Old City of Jerusalem is almost 1 square kilometre in area.
*Milton Science Park, Oxfordshire, UK.
* Mielec Industrial Park, Mielec, Poland
* The Guildford Campus of Guildford Grammar School, South Guildford, Western Australia
* Sardar Vallabhbhai National Institute of Technology (SVNIT), Surat, India
* Île aux Cerfs Island, near the east coast of Mauritius.
Peng Chau is a small island located off the north-eastern coast of Lantau Island, Hong Kong. It is known locally for its temples, fishing industry and seafood.
Peng Chau has an area of and a perimeter of about . The tallest point ... Island, Hong Kong
Conversion of units
Conversion of units is the conversion between different units of measurement for the same quantity, typically through multiplicative conversion factors which change the measured quantity value without changing its effects.
The process ...
* SI prefix
The International System of Units, known by the international abbreviation SI in all languages and sometimes pleonastically as the SI system, is the modern form of the metric system and the world's most widely used system of measurement. ... for the precise meaning of the prefix "k"
* Square Kilometre Array
The Square Kilometre Array (SKA) is an intergovernmental international radio telescope project being built in Australia (low-frequency) and South Africa (mid-frequency). The combining infrastructure, the Square Kilometre Array Observatory (SK ..., a proposed radio telescope
A radio telescope is a specialized antenna and radio receiver used to detect radio waves from astronomical radio sources in the sky. Radio telescopes are the main observing instrument used in radio astronomy, which studies the radio frequency ... in South Africa
South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring countr ... or Australia, which is intended to have a collecting area of approximately 1 km2
Units of area
SI derived units