What do the terms life expectancy, lifespan, longevity and health span mean?

In brief: Life expectancy is the average number of years that people in a given population can expect to live. Life duration, or lifespan, refers to the time between an individual’s birth and death. Longevity refers to an unusually long life. When it comes to ageing research, the emphasis is on healthy life years. These are defined as the number of years a person lives in optimal health and is able to live independently.

The terms life expectancy, lifespan, longevity and health span are often used interchangeably in everyday language. In ageing research, however, they describe different concepts.

Life expectancy is a statistical figure. It indicates the average number of years that people of a certain age can expect to live. It can be calculated, for example, at birth or later in life, and depends, amongst other things, on year of birth, gender, living environment, medical care and other demographic factors. Life expectancy therefore does not describe how old an individual person will actually become, but rather an average value within a specific population. According to the German Federal Statistical Office, life expectancy at birth in Germany, based on the 2022/2024 mortality table, was 78.5 years for men and 83.2 years for women (German Federal Statistical Office 2025).

Life duration or lifespan, on the other hand, describes the actual time between the birth and death of an individual.

Maximum lifespan describes the highest observed age of an individual. In humans, Jeanne Calment, who lived to the age of 122 years and 164 days, is considered the best-documented case of extreme longevity (Robin-Champigneul F, 2020). Whether there is a fixed biological upper limit to human lifespan is a matter of scientific debate. Research often cites a range of around 120 years (Dong X et al., 2016).

Longevity describes a life that is particularly long compared to the average for a species or population (De Benedictis G and Franceschi C, 2006). Today, it is frequently used as an umbrella term for research, medicine and technologies designed to enable a longer and, above all, healthier life. In reputable ageing research, the focus is less on the promise of unlimited life extension and more on the question of how people can live as long as possible in good health and independently.

Healthspan describes the period of a person’s life spent in good health. This means that he or she is, as far as possible, free from serious, chronic illnesses and significant age-related limitations. Ageing research is therefore not solely concerned with extending lifespan, but above all with increasing the number of healthy and independent years of life (Kaeberlein M, 2018).

Updated on 1.7.2026