What Is Population Density?
Population density is a measure of how many people live in a given area of land. It tells us whether a place is crowded (densely populated) or almost empty (sparsely populated).
The formula for calculating population density is:
The result is expressed as people per km² (or sometimes per square mile).
Examples:
- Bangladesh: population ~170 million, area ~147,570 km² → density ≈ 1,150 people/km² (one of the world's most densely populated countries)
- Mongolia: population ~3.4 million, area ~1,564,110 km² → density ≈ 2.2 people/km² (one of the world's most sparsely populated countries)
- Greenland: population ~57,000, area ~836,330 km² (ice-free) → density ≈ 0.07 people/km²
The world's most densely populated sovereign country is Monaco, a tiny city-state on the French Riviera, with about 26,000 people in just 2 km² — a density of roughly 26,000 people per km². By contrast, the entire continent of Antarctica has no permanent residents and a population density of zero (only temporary scientific research staff live there).
Densely Populated Areas
Some parts of the world have very high population densities. The most densely populated regions include:
- South and East Asia: The Ganges Plain in India, the valley of the Huang He (Yellow River) in China, the island of Java in Indonesia, and the Japanese coastal plains are among the most crowded places on Earth. Fertile soil, flat land, water supply, warm climate, and long histories of intensive agriculture support enormous populations.
- Western Europe: Countries such as the Netherlands, Belgium, and England have high densities due to long histories of trade, industrialisation, and urban development.
- Nile Valley (Egypt): Egypt is mostly desert, so almost the entire population of over 100 million people is squeezed into the narrow fertile strip along the Nile — one of the most extreme examples of uneven population distribution in the world.
Sparsely Populated Areas
Other parts of the world have very low population densities:
- Hot deserts: The Sahara, Arabian Desert, and Australian Outback are almost empty because of extreme heat, lack of water, and absence of fertile soil.
- Cold regions: The Arctic, Antarctic, Siberia, and northern Canada are very thinly populated because of harsh winters, permafrost, and the difficulty of growing food.
- Rainforests: Dense tropical rainforests like the Amazon are difficult to farm and settle in — though indigenous communities have lived there for thousands of years.
- High mountains: Steep, rocky terrain, cold temperatures, and thin soils make high mountain areas like the Himalayas and the Andes sparsely populated (though some valleys and plateaus are settled).
Factors Affecting Population Distribution
Population is not distributed randomly. Several factors explain why people are found in some areas but not others:
Physical factors (natural):
- Climate: Mild, moderate climates encourage dense settlement. Extreme cold, heat, or drought discourages it.
- Relief (terrain): Flat, lowland areas are easier to farm, build on, and travel across, so they tend to be more populated. Steep mountains and marshy ground are harder to use.
- Soil fertility: Fertile soils allow productive farming, which can support large populations. Poor, thin, or waterlogged soils limit farming.
- Water supply: Access to fresh water for drinking and irrigation is essential. The world's oldest civilisations grew up in river valleys for this reason.
Human factors:
- Industry and employment: Areas with mines, factories, or important services attract workers and build up large populations.
- Transport links: Good roads, railways, and port access make areas more attractive for settlement and trade.
- History: Cities that grew important centuries ago (as ports, capitals, or religious centres) often remain large today due to accumulated infrastructure and cultural importance.
It is important not to confuse population density with total population. China has one of the world's largest total populations (~1.4 billion), but its average population density (~150 people/km²) is not the highest, because China also has large areas of desert, mountain, and steppe where almost nobody lives. The densely populated eastern coastal provinces have very high local densities, while western Xinjiang and Tibet are almost empty. Always check whether a map is showing total population or population density.
Population Distribution Maps
Choropleth maps (maps shaded in different colours or intensities) are commonly used to show population density. Darker shading usually indicates higher density.
Dot maps place one dot to represent a fixed number of people (e.g. one dot = 100,000 people). Clusters of dots show dense populations; isolated or absent dots show sparse areas.
When reading population distribution maps, it is important to describe:
- Where the high/low density areas are.
- Patterns — for example, are dense areas along coasts, river valleys, or near mountains?
- Anomalies — anything that does not fit the general pattern.
Real world: The Nile Valley — extreme population concentration in Egypt
Egypt has a total population of over 100 million people but an area of around 1 million km² — giving an average density of about 100 people/km². However, this average is deeply misleading. Over 95% of Egyptians live in the Nile Valley and the Nile Delta, which together cover less than 5% of Egypt's land area. In this narrow fertile strip, actual population density exceeds 1,500 people/km². The rest of Egypt — the vast Sahara and Eastern Deserts — is almost completely empty. This makes Egypt one of the most extreme examples of uneven population distribution in the world: a high-density ribbon of settlement running through a near-empty desert nation.
Real world: The Netherlands — high density and land reclamation
The Netherlands is one of Europe's most densely populated countries, with about 510 people per km² — compared to the UK's 280 and France's 120. Yet much of the Netherlands was not even land originally: around 17% of the country was reclaimed from the sea using dykes and pumping systems (called polders). Despite its density, the Netherlands is wealthy, well-organised, and a major agricultural exporter, demonstrating that high population density does not automatically mean overcrowding or poverty. Careful planning, investment in infrastructure, and intensive farming methods allow the Netherlands to support its dense population sustainably.
Real world: Mongolia — the world's least densely populated country
Mongolia covers an area of about 1.56 million km² — larger than France, Germany, Spain, and Italy combined — yet has a total population of only about 3.4 million people. This gives a density of just 2.2 people/km². The reasons are entirely geographic: most of Mongolia is either the Gobi Desert in the south (too dry and hot for settled farming) or cold, windswept steppe grassland. The traditional lifestyle of Mongolian herders — following animals across large territories — does not require permanent settlements. Even today, roughly half of Mongolians outside the capital Ulaanbaatar are nomadic or semi-nomadic.
Where do you see this in real life? Look at your own region on a population density map. Are some areas much more densely populated than others? Try to identify why — is it because of rivers, flat land, historical ports, or industrial areas? Compare your country's average density with the density of the town or city nearest to you. The average often hides enormous variation between urban cores and rural hinterlands.
Practice Problems
A country has a population of 45 million people and an area of 300,000 km². Calculate its population density.
Show answer
Explain why Bangladesh has one of the world's highest population densities while Mongolia has one of the world's lowest.