# Glossary:Life expectancy

**Life expectancy** at a certain age is the mean additional number of years that a person of that age can expect to live, if subjected throughout the rest of his or her life to the current mortality conditions (age-specific probabilities of dying, i.e. the death rates observed for the current period).

Life expectancy being expressed as the number of years persons of different ages may expect to live, starting from age zero, **life expectancy at birth** is the mean number of years a newborn child can expect to live if subjected throughout his or her life to the current mortality conditions, the probabilities of dying at each age.

Any later age can also be chosen as a starting point; the **total expected life span** is then this age plus the life expectancy at that age, the number of years a person of that age may expect to live if mortality patterns stay unchanged. Life expectancy is normally calculated separately for all age levels, as well as for males, females and the total population.

## Further information

- Mortality (ESMS metadata file — demo_mor_esms)