Life expectancy at birth
The average number of years a newborn would live, if death rates at every age stayed exactly as they are today.
In short
It is a snapshot of today's mortality, not a prediction for any child born this year. Most children born today will live in a world with different death rates than the ones used to calculate this number.
How it's calculated
Life expectancy at birth almost always uses the "period" method: it takes one year's death rates at every age and asks how long a newborn would live if those rates never changed for the rest of their life. The result is a single number constructed from a hypothetical lifetime, not an observation of how long people actually lived.
Note A rising period life expectancy usually means mortality is falling across most ages, from infancy through old age, not that ageing itself has slowed down.
Typical values
Why it matters here
Life expectancy is one half of what shapes a ridgeline's height over time. Falling death rates, alongside births, are a large part of why so many countries grew fastest in the 20th century, even before fertility began to fall. Paired with total fertility rate, it explains most of the shape of the last 200 years on the canvas.
The global average life expectancy at birth was around 29 years in 1800 — not because most people died young, but because very high infant and child mortality pulled the average down sharply. Adults who survived childhood often lived into their 50s or 60s. The rise to over 73 years globally by 2023 is driven mainly by the near-elimination of many early-life deaths, a transformation that happened mostly after 1950. The WHO Global Health Observatory publishes current life expectancy estimates by country, sex, and year.
Variation within countries
A national life expectancy figure hides large internal differences. Within most countries, life expectancy varies substantially by income, education, urban versus rural residence, and ethnicity. The gap between the longest- and shortest-lived groups within a single country is often 10 to 20 years — larger than the gap between many pairs of countries. This means the single national number, while useful for comparisons, is only the beginning of understanding who lives longer and why.
Frequently asked questions
What does life expectancy at birth mean?
Life expectancy at birth is the average number of years a newborn can expect to live if the age-specific death rates observed in the year of birth remained constant throughout their lifetime. It is a summary measure of current mortality conditions, not a personal prediction. Country-level series back to 1950 are available from the UN World Population Prospects mortality tables.
What is the difference between period and cohort life expectancy?
Period life expectancy uses a single year's death rates across all ages — it is a snapshot. Cohort life expectancy tracks an actual birth year group through their real mortality experience over decades. Period figures are published annually and are much more common; cohort figures are only available retrospectively. The Human Mortality Database maintains detailed cohort data for countries with long civil registration records.
Why did global life expectancy rise so sharply in the 20th century?
Global life expectancy roughly doubled between 1900 and 2000, driven primarily by sharp falls in infant and child mortality. The main drivers were improved sanitation and clean water access, vaccines and antibiotics, better nutrition, and the expansion of basic healthcare to more of the world's population. Our World in Data charts this rise in detail across countries and regions.
How does life expectancy relate to population growth?
Rising life expectancy reduces death rates, which is one of two main drivers of population growth alongside birth rates. When life expectancy improves faster than fertility falls, populations grow. This is why many countries in sub-Saharan Africa are still growing rapidly even as fertility is beginning to decline. The GBD 2021 study in The Lancet analyses global trends in life expectancy and the causes of improvement in detail.