In simple terms
Life expectancy at birth is the number of years a newborn would live if the death rates of its birth year stayed the same for the rest of its life.
So it summarizes current mortality rather than forecasting any individual life. A baby born in a high-life-expectancy year has no guarantee, and a baby born during an epidemic is not sentenced by the figure.
How it works
The calculation takes age-specific death rates across the whole population in one year and applies them to a hypothetical group of newborns to see how long they would last. The World Bank, which publishes the indicator using United Nations Population Division data, notes that for many countries the total is derived from separate male and female estimates reported by national statistical offices or by Eurostat.
Because it is anchored to a single year’s mortality, the figure drops quickly during a shock and recovers when the shock passes. That is a feature of the construction rather than a sign of bad data, and it is why a year-on-year change should be read as a change in death rates rather than a change in human longevity.
Numbers differ sharply by sex and country. In the United States in 2024, life expectancy at birth was 79.0 years overall, 76.5 years for males and 81.4 years for females.
Why it matters
It is the most widely used single summary of a population’s health, which makes it the backbone of comparisons between countries, of pension and insurance design, and of development targets. Its weakness follows from its strength: one number says nothing about how many of those years are spent in good health, or about gaps between groups inside the same country.
Where you’ll see it
- World Bank and United Nations country indicators
- National statistics office mortality releases and life tables
- Pension, insurance and long-term care projections
- News comparisons of health outcomes between countries
Example
A country whose life expectancy at birth is 72 years is reporting that, under this year’s death rates, a newborn would live 72 years on average. It is not reporting that people there die at 72.
Often confused with
Lifespan, meaning how long a person actually lives. Life expectancy at birth describes a whole population under one year’s death rates, so it is not a prediction for any individual.
Key facts
- Life expectancy at birth is the number of years a newborn would live if the mortality patterns at the time of its birth stayed the same throughout its life.1
- The World Bank publishes the indicator using United Nations Population Division figures, national statistical office data and Eurostat demographic statistics.1
- For many countries the total is derived from separate male and female life expectancy estimates.1
- In the United States in 2024, life expectancy at birth was 79.0 years overall: 76.5 years for males and 81.4 years for females.2
This entry explains a medical term. It is not medical advice. If you are concerned about your health, speak with a qualified health professional.
Related concepts
In the news
Quick checkDoes life expectancy at birth predict how long a particular baby will live?Show answer
No. It applies one year's death rates to a hypothetical group of newborns, so it summarizes current mortality for a population.
Sources
- World Bank DataBank. Metadata Glossary: Life expectancy at birth, total (years), series SP.DYN.LE00.IN. Updated 8 October 2026 (accessed Accessed 21 October 2026)
- CDC National Center for Health Statistics. FastStats: Life Expectancy, from Mortality in the United States, 2024. Reviewed 29 September 2026 (accessed Accessed 21 October 2026)
Editorially reviewed by Specialty Digest Editorial TeamLast reviewed October 21, 2026Researched and drafted with AI assistanceReport an issue