Life Expectancy: Meaning, Data, and Best Predictors of Long Life

You’ve probably seen life expectancy numbers quoted in headlines — 79 years in the U.S., 81 for women, 73 globally. But those averages hide a fascinating truth: the older you get, the longer you’re statistically likely to live. This guide walks through what life expectancy really means, how it shifts as you age, and which factors actually predict a long life — no oversimplifications, just the data.

Global life expectancy at birth (2026): 73.8 years ·
U.S. life expectancy at birth (2024): 79.0 years ·
Female advantage in the U.S.: 81.4 vs 76.5 years

Five key data points that frame the conversation about how long we live and what changes as we age.

What is the meaning of life expectancy?

How is life expectancy calculated?

Life expectancy is the average number of years a person could expect to live if they were exposed to the sex- and age-specific death rates prevailing in a specific year and place, according to the World Health Organization (WHO metadata registry). It’s a summary measure of the mortality pattern at a given time. The CDC (National Center for Health Statistics) uses age-specific death rates to calculate remaining years at any age.

Why does life expectancy differ by age?

• Life expectancy at birth includes infant and child mortality — a 70-year-old has already survived those risks.
• Actuarial tables show that remaining years increase the older you get (the “actuarial paradox”).
• Conditional survival probability: the chance of surviving additional years rises after surviving an initial period (Cancer Australia NCCI).

Bottom line: Actuarial tables show that life expectancy is a moving target: the longer you’ve already lived, the higher your remaining years.

How long can a 70 year old woman expect to live?

Life expectancy at 70 vs. birth

A 70-year-old woman in the U.S. can expect to live approximately 16–18 more years, based on CDC life tables. That’s notably more than the 11–13 years a newborn might estimate if they only looked at the 81.4-year average — because she’s already made it past early-life risks.

• Global variation: women in Japan and Spain have even higher life expectancy at 70 (OECD data).
• At age 70, the sex gap narrows but doesn’t disappear: women still outlive men by about 2–3 years (CDC).

Gender differences in later-life survival

Women outlive men at all ages in every country with reliable data. The OECD (Society at a Glance 2024) reported that in 2021 the OECD average life expectancy at birth was 83.0 years for women vs 77.6 for men — a gap of 5.4 years. Biological, behavioral, and social factors all play a role.

The implication: age is a more powerful predictor of remaining years than sex or global averages.

What percentage of 80 year olds live to 90?

Factors that increase survival to 90

According to Social Security Administration actuarial tables, approximately 30–40% of 80-year-olds in the United States survive to age 90. The probability is higher for women and for those without chronic conditions.

• Genetics account for an estimated 20–30% of longevity variation.
• Lifestyle factors — diet, exercise, not smoking — are major modifiable predictors.
• Absence of heart disease, cancer, or diabetes dramatically increases the odds.

Health incidents such as hospital-acquired infections can diminish survival odds, as seen in the experience of Leslie Ash.

Most common cause of death in 80-year-olds

The CDC (National Vital Statistics Report) lists heart disease, cancer, and stroke as the three leading causes of death after age 70. Together they account for more than half of all deaths in this age group.

Bottom line: Data from the Social Security Administration confirms that roughly one in three 80-year-olds will reach 90, with the key factor being avoidance of chronic disease.

What is the biggest indicator of long life?

What’s the best predictor of your longevity?

Current age is one of the strongest predictors: the older you are, the longer your remaining life expectancy. This isn’t tautology — it’s conditional survival. As highlighted by Clinical Cancer Research (conditional survival analysis), survival probabilities change substantially after a patient has already survived an initial period.

• Genetic factors: about 20–30% of longevity is heritable.
• Lifestyle: not smoking, moderate exercise, and a balanced diet add years.
• Socioeconomic factors: education, income, and healthcare access matter.

A personal health crisis, such as a cancer diagnosis and recovery, can alter longevity outlook, as documented in the biography of Cobie Smulders.

Is 70 years a long life?

Globally, reaching 70 is above the world average of 73.8 years. But in developed nations, 70 is now considered “young-old.” The WHO (Healthy Life Expectancy HALE definition) focuses on healthspan, not just lifespan — many people in their 70s enjoy active, healthy lives.

The implication: Healthy life expectancy, not just lifespan, should guide personal health goals.

At what age do most people pass away?

What birthday lives the longest?

In developed countries, the highest death count in a given year typically occurs in the late 70s to early 80s for men and early to mid-80s for women. The median age at death is around 80–85 for women and 75–80 for men, based on OECD life expectancy at birth data.

At what age do most people start feeling older?

Subjective aging varies widely. Surveys often report that people begin to “feel old” around 68–70, but this is highly individual. The Britannica overview of life expectancy notes that period measures don’t account for the diversity of personal aging trajectories.

Bottom line: Mortality statistics indicate that the median age at death is in the late 70s to mid-80s, but individual outcomes vary based on genetics, lifestyle, and chance.

“Life expectancy is a summary measure of the mortality pattern prevailing at a given time in the remaining years of life at a certain age.”

— World Health Organization

“Period life expectancy at birth is a hypothetical period measure, not a prediction for any one individual.”

— Britannica

“Conditional survival is useful because survival probabilities can change substantially after a patient has already survived an initial period.”

— Clinical Cancer Research

The data tells a clear story: life expectancy is a moving target that increases as you age. For a 70-year-old woman, the next 16–18 years are a realistic expectation. For an 80-year-old, hitting 90 is a coin flip with odds in your favor if you avoid chronic disease. The strongest predictor of longevity is simply the number of candles on your cake. For readers in the U.S. and other high-income countries, the choice is not about defying mortality but about extending healthspan: invest in lifestyle changes early, because the conditional probability of a long life rises with every year you stay active and disease-free.

For a detailed breakdown of how these figures apply specifically to the United Kingdom, see this UK life expectancy guide.

Frequently asked questions