The FRED Blog has used World Bank data to discuss infant mortality and life expectancy and refugee populations across groups of countries, economies, or territories classified by their level of income. Today, we discuss how these income categories are assigned.

The FRED graph above shows annual population growth data between 1961 and 2023 for the four income categories defined by the World Bank: high (blue line), upper middle (red line), lower middle (green line), and low (purple line).

Each country's income is measured through its gross national income (GNI), the economic value added by all national producers (plus and minus some adjustments). The income figure is converted from various local currencies to US dollars, then divided by the number of persons in the total population and compared against a series of numerical thresholds for each group. For example, at the time of this writing, a low-income economy is defined as one with a GNI per person of $1,145 or less.

The threshold values separating each income category are updated every year to account for price inflation. Also, because income levels do change over time, some countries move into different categories. For example, all South Asian countries were classified as low-income countries in 1987, whereas in 2023 only one in eight were in that category.

This FRED Blog post is adapted from the World Bank's Data Blog post "World Bank country classifications by income level for 2024-2025."

How this graph was created: Search FRED for and select "Population Growth for High Income Countries." Next, click the "Edit Graph" button and then the "Add Line" tab to search for and add "Population Growth for Upper Middle Income Countries." Repeat that last step two more times to add the "Population Growth for Lower Middle Income Countries" and the "Population Growth for Low Income Countries" to the graph.

Suggested by Diego Mendez-Carbajo.