Chronological Age
Definition
Chronological age is the amount of time that has passed since a person was born, usually measured in years. It is a calendar-based measure, not a direct measure of physiological state, function, or biological ageing. [1] [2]
Why It Matters in Ageing Research
Chronological age remains important because it is the standard reference point for comparing people and populations. But it is limited: people of the same age can differ a great deal in health status, function, and biomarker patterns. That is why ageing research often contrasts chronological age with biological age or functional measures. [1] [3]
Common Confusion
- Chronological age is not the same as biological age.
- People with the same chronological age do not necessarily age at the same biological rate.
- Chronological age is useful for population comparisons, but less precise for judging individual ageing differences.
Related Reading
References
- Salih, A., et al. (2023). Conceptual overview of biological age estimation. https://pmc.ncbi.nlm.nih.gov/articles/PMC10187689/
- Baars, J. (2013). Aging and Time. http://www.janbaars.nl/wp-content/uploads/Aging-and-Time-Chapter-01-Jan-Baars.pdf
- Witzel, D. D., et al. (2025). Age and inflammation: Insights on "age three ways" from population cohorts. https://www.sciencedirect.com/science/article/abs/pii/S0889159125001035
This glossary entry is provided for educational purposes only and does not constitute medical advice.