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 theNorthern Hemisphere, where 67% of Earth's land area is.
Population density is population divided by totalland area, sometimes including seas and oceans, as appropriate.[1]
Low densities may cause anextinction vortex and further reduce fertility. This is called theAllee effect after the scientist who identified it. Examples of the causes of reduced fertility in low population densities are:[2]
Population density (people per square kilometre) map of the world in 2020
Population density is the number of people per unit of area, usually transcribed as "per square kilometre" or square mile, and which may include or exclude, for example, areas of water or glaciers. Commonly this is calculated for acounty,city,country, anotherterritory or theentire world.
World population is around 8,000,000,000[3] and theEarth's total area (includingland 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, includingAntarctica. 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 arecity-states,microstates and urbandependencies.[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 highurbanization level, with an economically specializedcity population drawing also on rural resources outside the area, illustrating the difference between high population density andoverpopulation.
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 asDubai, 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 (particularlySoutheast Asia); Africa'sLagos,Kinshasa, andCairo; South America'sBogotá,Lima, andSão Paulo; andMexico City andSaint 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 theagglomeration ormetropolitan area (the latter sometimes including neighboring cities).
In comparison, based on a world population of 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 an area of 8,000 square kilometres (3,100 sq mi) a little less than the land area ofPuerto Rico, 8,868 square kilometres (3,424 sq mi).
This populationcartogram 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. RetrievedMarch 12, 2009.
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