Lifespan vs Healthspan vs Maximum Lifespan

Four terms that get mixed up

News stories and product pages often use "lifespan," "life expectancy" and "longevity" as if they were the same thing. They are not. Each answers a different question, and mixing them up is a common way for claims to mislead. This page is education only. Evidence labels follow how we label evidence in longevity research.

Life expectancy is an average, not a limit

The WHO defines life expectancy at birth as the average number of years a person could expect to live if exposed to the sex- and age-specific death rates of a given year in a given country. It is derived from life tables and reflects the overall mortality level of a population. [1] Because it is an average across a whole population, it is not a promise for any one person and it is not the same as the longest a person can live.

Healthspan is the shortfall that matters

Healthy life expectancy asks how many of those years are spent in "full health." [2] A study of WHO data from 183 member states found the gap between life expectancy and healthy life expectancy widened over two decades, reaching 9.6 years, with the largest gap (12.4 years) in the United States. [3] See healthspan and lifespan for how this gap is measured and its limits.

Maximum lifespan: is there a ceiling?

This is a real scientific debate, not a settled fact.

• Evidence for a limit. A 2016 analysis of global demographic data reported that gains in survival tend to flatten after about age 100, and that the age at death of the world's oldest person had not increased since the 1990s. The authors concluded that the maximum lifespan of humans is fixed and subject to natural constraints. [4]
• Challenges to that view. Other researchers published replies titled "Is there evidence for a limit to human lifespan?" and "Questionable evidence for a limit to human lifespan." [5][6]
• A separate finding on extreme old age. A study of all 3,836 documented people aged 105 and older in Italy (2009 to 2015) found that the yearly risk of death was essentially constant beyond age 105, which the authors described as the best evidence to date for a mortality plateau in humans. [7]
• The record. One author notes that only one woman has been validated as reaching 122 years in recorded scientific history. [8]

Label: mixed. The data show that few people reach very old ages and that the record has not been broken for decades, but experts disagree about whether a hard limit exists. None of this tells any individual how long they will live.

Why the difference matters for claims

• A product or clinic claiming to "extend lifespan" should say whether it means average life expectancy, an individual's years, healthspan, or maximum lifespan. Most human research cannot measure maximum lifespan at all, because trials are shorter than a human life.
• Lifespan results in mice are preclinical (cells or animals only) and are not evidence of benefit in people. See aging in animals vs humans.
• Practical, evidence-based habits for the years you live are covered in the Wellness guide to healthy aging.