<P> For humans, population density is the number of people per unit of area, usually quoted per square kilometer or square mile (which may include or exclude, for example, areas of water or glaciers). Commonly this may be calculated for a county, city, country, another territory or the entire world . </P> <P> The world's population is around 7,500,000,000 and Earth's total area (including land and water) is 510,000,000 square kilometers (197,000,000 sq. mi .). Therefore, the worldwide human population density is around 7,500,000,000 ÷ 510,000,000 = 14.7 per km (38 per sq. mi). If only the Earth's land area of 150,000,000 km (58,000,000 sq. mi .) is taken into account, then human population density increases to 50 per km (129 per sq. mile). This includes all continental and island land area, including Antarctica . If Antarctica is also excluded, then population density rises to over 55 people per km (over 142 per sq. mile). However, over half of the Earth's land mass consists of areas inhospitable to human habitation, such as deserts and high mountains, and population tends to cluster around seaports and fresh - water sources . Thus, this number by itself does not give any helpful measurement of human population density . </P> <P> Several of the most densely populated territories in the world are city - states, microstates and dependencies . 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 . </P> <P> 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 . Most of the most densely populated cities are in Southeast Asia, though Cairo and Lagos in Africa also fall into this category . </P>

Where do population densities on earth tend to be higher