Ageing and dependency ratios: how the numbers are calculated
The old-age dependency ratio is the number of people aged 65 or more for every 100 people aged 15 to 64. The child dependency ratio is the number of children under 15 for every 100 people aged 15 to 64. Both are ratios of age groups, not of workers and dependants.
The calculation
Both ratios divide an age group by the number of people aged 15 to 64 and multiply by 100:
- Old-age dependency ratio: people aged 65 or more, per 100 people aged 15 to 64.
- Child dependency ratio: children under 15, per 100 people aged 15 to 64.
- Total dependency ratio: the two added together.
On 1 January 2026, by the UN projection, the world has an old-age dependency ratio of 16.1 and a child dependency ratio of 37.2. In 1950 the values were 8.4 and 57.7.
Japan, one of the oldest countries, has an old-age dependency ratio of 51.2 on the same date.
What the ratios do not measure
The age limits are conventions. Many people aged 15 to 64 study, care for family or cannot work, and many people over 65 work. The ratios describe how a population is spread across ages, which shapes pensions, health care and schools, but they are not counts of workers or of people who depend on others.
Other measures of ageing
- Median age: half the population is older, half younger. It is 30.4 years for the world in 2023.
- Share aged 65 or more: 10.5% of the world on 1 January 2026.
- Share aged 80 or more, and any age threshold you choose, in the ageing tool.
Each measure on the site says which population it is divided by, so a share and a ratio are never confused.
Last updated 26 October 2026