Age structure

Map 1. Dependency ratio, 2021

Regional distribution of dependency ratios and trends over time

In 2021, for every 100 persons of working age there were 54 children or older people. The dependency ratio was highest in some African countries and in Afghanistan. In all these cases, the high ratios were a result of a very high child dependency. In Africa as a whole, the child dependency ratio alone was 72 per cent. By contrast, the lowest dependency ratios were found on the Arabian Peninsula and in the Caribbean. Several developed economies, most notably Japan, show rising dependency ratios due to increasing old-age dependency.

Globally, 65 per cent of people were of working age in 2021. Fifty years ago, this number was 57 per cent. The marked change is that the proportion of children has decreased from 38 per cent in 1971 to 25 per cent while the proportion of older persons has increased from 5 to 10 per cent. People above the age of 64 are projected to make up 16 per cent of the global population by 2050.

Figure 1. World population by age group

Young age cohorts are smaller in developed economies

The age structure in developing economies is pyramid shaped with older age classes successively smaller than younger classes. In developed economies, however, the biggest age groups are 30 to 59 years old. A temporarily accelerated decrease in births worldwide during the COVID-19 pandemic is reflected by the size of groups of children under 5.

Globally, in 2021, 59.4 per cent of people over 75 years were women, while only 48.5 per cent of children were girls. This imbalance in the sex distribution can be seen in both developed and developing economies.

Figure 2. Population pyramids, 2021

Working age people support fewer children but more older persons

In most economies, the age structure has seen a trajectory over time, where dependency ratios first decrease, due to shrinking proportions of children, and later increase, as more people reach an age of over 64.

In most regions of the world, the bulk of the dependency ratio decrease has already taken place, and further decreases in the child dependency ratio are projected to be more than offset by increases in the old-age dependency ratio. In Africa, however, the decline of the dependency ratio is expected to continue beyond 2050. By 2050, the dependency ratio in Africa is projected to fall to 60 per cent from 78 per cent in 2021. In developed economies, dependency ratios are already increasing and are projected to reach 73 per cent by 2050.

Figure 3. Dependency ratio by age structure
Note: The total dependency ratio is the sum of the child and old-age dependency ratios.

Concepts and definitions

In this section, the term “persons of working age” refers to persons aged from 15 to 64 years. The term “children” refers to persons under the age of 15. The term “older persons” refers to persons over the age of 64.

The dependency ratio is defined as the number of children and older persons per hundred persons of working age. It can be expressed as the sum of the child dependency ratio and the old-age dependency ratio.

The child dependency ratio is defined as the number of children per hundred persons of working age. The old-age dependency ratio is defined as the number of older persons per hundred persons of working age.

Summary tables

Table 1. Age structure and dependency ratio by group of economies
    Table 2. Age structure by group of economies, 2021
      Table 3. Female population by age class, 2021