Population Density
Number of people per unit area.
Formula
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Example
8 million people in 800 km² gives a density of 10 000 people/km².
How it works
Population density tells you how crowded a place is by comparing how many people live there to the size of the land they occupy. It works because the same population spread over a larger area gives a lower density, while the same population in a smaller area gives a higher density. Dividing population by area makes the result easy to compare between regions of different sizes.
When to use it
Use this formula when comparing how populated cities, districts, countries, or habitats are. It is also useful in planning services such as housing, transport, and schools, because denser places usually need more infrastructure per square kilometre.
Worked example, step by step
A town has a population of 250,000 people and covers an area of 500 km². D = P / A D = 250,000 / 500 D = 500 So the population density is 500 people per km².
Common mistakes to avoid
- Using the wrong area unit, such as mixing km² with m²
- Reversing the formula and dividing area by population
- Forgetting to include the unit 'people per km²' or similar in the final answer
Did You Know?
Monaco packs over 18,000 people per square kilometer, while Mongolia has barely two.
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