Measurement of population per unit area or unit volume
Population density (people per square kilometre) by country in 2023Population density (people per square kilometre) map of the world in 1994. In relation to the equator it is seen that the vast majority of human population lives in the Northern Hemisphere, where 67% of Earth's land area is.
Population density is population divided by total land area, sometimes including seas and oceans, as appropriate.[1]
Low densities may cause an extinction vortex and further reduce fertility. This is called the Allee effect after the scientist who identified it. Examples of the causes of reduced fertility in low population densities are:[2]
Population density is the number of people per unit of area, usually transcribed as "per square kilometer" or square mile, and which may include or exclude, for example, areas of water or glaciers. Commonly this is calculated for a county, city, country, another territory or the entire world.
The world's population is around 8,000,000,000[3] and the Earth's total area (including land and water) is 510,000,000 km2 (200,000,000 sq mi).[4] Therefore, the worldwide human population density is approximately 8,000,000,000 ÷ 510,000,000 = 16/km2 (41/sq mi). However, if only the Earth's land area of 150,000,000 km2 (58,000,000 sq mi) is taken into account, then human population density is 53/km2 (140/sq mi). This includes all continental and island land area, including Antarctica. However, if Antarctica is excluded, then population density rises to over 58 per square kilometre (150/sq mi).[1]
World environments map provided for comparison with maps above
Several of the most densely populated territories in the world are city-states, microstates and urban dependencies.[6][a] In fact, 95% of the world's population is concentrated on just 10% of the world's land.[7] These territories have a relatively small area and a high urbanization level, with an economically specialized city population drawing also on rural resources outside the area, illustrating the difference between high population density and overpopulation.
Deserts have very limited potential for growing crops as there is not enough rain to support them. Thus, their population density is generally low. However, some cities in the Middle East, such as Dubai, have been increasing in population and infrastructure growth at a fast pace.[8]
Mongolian Steppes. Mongolia is the least densely populated country in the world due to its harsh climate as a result of its geography.[9]
Cities with high population densities are, by some, considered to be overpopulated, though this will depend on factors like quality of housing and infrastructure and access to resources.[10] Very densely populated cities are mostly in Asia (particularly Southeast Asia); Africa's Lagos, Kinshasa, and Cairo; South America's Bogotá, Lima, and São Paulo; and Mexico City and Saint Petersburg also fall into this category.[11]
Monaco is currently the most densely populated nation in Europe.
City population and especially area are, however, heavily dependent on the definition of "urban area" used: densities are almost invariably higher for the center only than when suburban settlements and intervening rural areas are included, as in the agglomerationormetropolitan area (the latter sometimes including neighboring cities).
In comparison, based on a world population of 7.8 billion, the world's inhabitants, if conceptualized as a loose crowd occupying just under 1 m2 (10 sq ft) per person (cf. Jacobs Method), would occupy a space a little larger than Delaware's land area.[citation needed]
This population cartogram of the European Union (2007–2012) uses areas and colors to represent population.Living population density by country
Although the arithmetic density is the most common way of measuring population density, several other methods have been developed to provide alternative measures of population density over a specific area.
Arithmetic density: The total number of people / area of land
^Department of Economic and Social Affairs Population Division (2009). "World Population Prospects, Table A.1"(PDF). 2008 revision. United Nations. Retrieved March 12, 2009.
Macau (China)
Monaco
Singapore
Hong Kong (China)
Gaza Strip (Palestine)[b]
Gibraltar (UK)[c]
Bahrain
Vatican City
Malta
Maldives
Bangladesh
Taiwan
Rwanda
Netherlands
South Korea
Burundi
India
Haiti
Belgium
Philippines
