To read a population structure diagram, first find what each bar measures and when, then describe the shape, then use figures. This appears throughout population and settlement evidence and in questions about ageing, youth and planning for services.
How do you read the diagram step by step?
- Read the title and date. A pyramid for 2020 and one for 2050 are different evidence.
- Read the axis label. Bars may show a percentage of the total population, or a number such as millions of people. They are not the same.
- Check the age groups. Note whether bands are 5-year or 10-year groups and where the oldest group starts.
- Describe the shape. Say where it is widest, where it narrows and whether the two sides are similar.
- Add a figure. Quote a value with its unit, such as “about 11% of the population”.
- Say what it suggests and what it cannot show.
Worked example
Country A, 2020 (invented data). Bars show percentage of the total population.
| Age group | Share of population |
|---|---|
| 0 to 14 | 22% |
| 15 to 64 | 68% |
| 65 and over | 10% |
Describe it: In 2020, 68% of the population is aged 15 to 64, the largest group. 22% is under 15 and 10% is 65 and over.
Dependency ratio: dependants = 22% + 10% = 32%. Then 32 ÷ 68 = 0.4706, so about 47 dependants for every 100 people of working age.
Meaning: the country has a larger working-age group than dependants, so the load on workers is moderate. The diagram does not say how many of the 15 to 64 group are in paid work, so we cannot say more about the economy.
The mistake to watch for
Mistaken answer: “The bar for 15 to 19 is 4.2, so there are 4.2 million girls aged 15 to 19.”
The axis said ”% of total population”, not millions. Reading it as a count gives a wrong claim.
Correction: if the total population is 8 million, then 4.2% of 8,000,000 = 336,000 girls. Always match your wording to the axis: “4.2% of the population”.
Self-check
1. Country B, 2015 (invented): 0 to 14 is 25%, 15 to 64 is 70%, 65 and over is 5%. Work out the dependency ratio to the nearest whole number.
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Dependants = 25 + 5 = 30. Then 30 ÷ 70 = 0.4286, so about 43 dependants per 100 people aged 15 to 64.2. In the same data, what is the old-age dependency ratio (65 and over compared with 15 to 64)?
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5 ÷ 70 = 0.0714, so about 7 per 100 people aged 15 to 64.3. A pyramid axis reads ”% of total population” and a bar is 6%. What is wrong with writing “6 people”?
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The bar shows a share of the total, not a number of people. Write "6% of the population" and, if the total is given, multiply to find a count.Where does this lead next?
Once you can read the structure, the next question is why it changes. Continue with explaining a migration factor.
You can test your own figures in the statistics and distribution explorer. If you often mix up percentages and counts under exam pressure, a teacher can drill axis-reading with you in IGCSE Geography one-to-one tuition.