ATLAS · FUSION VIEW
Prosperity & Family Size
Fertility rate as colour, income per person as bubbles. The single clearest pattern in world demography — the richer a country, the fewer children per woman — laid over one map, with the exceptions made obvious.
COLOUR
Fertility Rate
Average births per woman over a lifetime, World Bank. About 2.1 is the replacement level.
World Bank Open Data · 2024
BUBBLE SIZE
GDP per capita
GDP divided by population, current US$, World Bank.
World Bank Open Data · 2024
How strongly do they move together?
Across the 214 countries with both figures, fertility rate and gdp per capita move in opposite directions a strong amount — as one rises, the other tends to fall (correlation r = -0.78). That’s a clear, dependable pattern; the map below makes it visible at a glance.
Correlation is measured across the 214countries that have both figures, in each metric’s own scale (log scale where the map uses one). Correlation is not causation — it only measures whether the two tend to track each other.
Deep green marks high fertility; the largest bubbles mark the richest economies. The two are almost mirror images — this is the demographic transition, one of the most reliable relationships in all of social science. Big bubbles sit on the palest, lowest-fertility ground. The countries to look twice at are the ones with a large bubble AND deep colour — wealth that has not yet pulled family size down — and the rare poor country that has already fallen below replacement.
Who fits the pattern — and who breaks it
Two ways to read the map. On the left, the countries that most clearly follow the relationship; on the right, the ones that most defy it — the exceptions worth a closer look.
Understand the underlying numbers
ATLAS · FIELD GUIDE
The Replacement Rate, and Why 2.1 Is the Most Important Number in Demography
Fertility rate decides whether a nation grows, holds steady, or slowly shrinks. A plain-language guide to what 'births per woman' means, why the magic number is about 2.1 rather than 2.0, and how to read the world map of a statistic that quietly shapes the next century.
ATLAS · FIELD GUIDE
GDP per Capita, and Why It Isn't the Same as How Rich People Are
GDP per capita is the standard yardstick for comparing how wealthy countries are — but it's an average that hides as much as it reveals. A plain-language guide to what it measures, why 'current US dollars' makes some comparisons misleading, and how to read the world map of it without overreaching.
See each layer on its own
TWO LAYERS, ONE MAP
Try another pairing, or build your own in the live Atlas.