How is biological age measured?

Biological age can be estimated using epigenetic clocks (DNA methylation patterns), blood biomarker panels, physiological tests like VO2 max and grip strength, and telomere length testing. Different methods measure different aspects of aging and produce different estimates.

Can you reduce your biological age?

Research suggests biological age markers can be influenced by lifestyle, particularly regular exercise, quality sleep, and a nutrient-dense diet. However, the size of these effects and how durable they are is still being studied. Claims of reversing biological age by large amounts should be evaluated critically.

What is an epigenetic clock?

An epigenetic clock is a biological age measurement tool that uses patterns of DNA methylation (chemical tags on DNA that change predictably with age) to estimate a person's biological age. Examples include the Horvath Clock, GrimAge, and DunedinPACE. These clocks are among the most validated methods for estimating biological age.

Longevity Fundamentals

What Is Biological Age?

Biological age measures how old your body is functionally, not how long you have been alive. Here is how it is measured and why it matters more than your birth year.

Updated June 18, 2026

Two people born in the same year can have dramatically different biological profiles. One may have the cardiovascular capacity, inflammatory markers, and cellular health of someone ten years younger. The other may show markers of aging that resemble someone a decade older. This is the distinction between chronological age and biological age.

Chronological Age vs Biological Age

Chronological age: the number of years since birth. It is fixed and increases at the same rate for everyone.
Biological age: a measure of how old the body is functionally, based on objective biological measurements. It can be younger or older than chronological age and can change over time in response to lifestyle and interventions.

Biological age is not a single number derived from a single test. It is an estimate based on a combination of biomarkers that correlate with the aging process. Different measurement systems use different inputs and produce different estimates.

How Biological Age Is Measured

Several methods are used to estimate biological age:

Epigenetic clocks: these measure patterns of DNA methylation (chemical modifications to DNA) that change predictably with age. The Horvath Clock (2013) was the first widely validated epigenetic clock. Newer clocks like DunedinPACE and GrimAge are designed to predict healthspan decline, not just age.
Blood biomarker panels: companies like Levine and others have built biological age calculators using standard blood markers (glucose, CRP, albumin, creatinine, etc.) combined into composite scores.
Physiological assessments: VO2 max, grip strength, walking speed, and lung function all correlate with biological aging and can be incorporated into biological age estimates.
Telomere length: the protective caps at the ends of chromosomes shorten with age and with cellular stress. Shorter telomeres are associated with older biological age, though telomere-based testing is more variable than epigenetic methods.

What Biological Age Can Tell You

Biological age measurements are useful in two main ways:

As a snapshot of current biological status: knowing your biological age relative to your chronological age can motivate and direct behavior change.
As a tracking tool: measuring biological age at intervals can show whether lifestyle interventions are having a measurable effect at the cellular level.

Limitations

Biological age tests vary significantly in methodology, accuracy, and what they measure. No single test gives a complete picture of aging. Commercial biological age tests should be interpreted with caution, and results discussed with a qualified healthcare professional. Research into biological aging clocks is active and evolving.

Can Biological Age Be Reduced?

Research suggests that biological age as measured by epigenetic clocks can be influenced by lifestyle. Studies have shown associations between regular exercise, caloric restriction, quality sleep, and stress reduction and more favorable epigenetic aging markers. However, the magnitude of these effects in healthy adults, and the durability of improvements, are still being studied.

Claims that any specific intervention can reliably reverse biological age by a set number of years should be viewed skeptically. The research is real but early-stage, and many commercial products overstate what is established.

Frequently Asked Questions

What is biological age?: Biological age is an estimate of how old your body is functionally, based on objective biological measurements rather than the number of years since birth. It can be younger or older than chronological age and can change over time in response to lifestyle, environment, and interventions.
How is biological age measured?: Biological age can be estimated using epigenetic clocks (DNA methylation patterns), blood biomarker panels, physiological tests like VO2 max and grip strength, and telomere length testing. Different methods measure different aspects of aging and produce different estimates.
Can you reduce your biological age?: Research suggests biological age markers can be influenced by lifestyle, particularly regular exercise, quality sleep, and a nutrient-dense diet. However, the size of these effects and how durable they are is still being studied. Claims of reversing biological age by large amounts should be evaluated critically.
What is an epigenetic clock?: An epigenetic clock is a biological age measurement tool that uses patterns of DNA methylation (chemical tags on DNA that change predictably with age) to estimate a person's biological age. Examples include the Horvath Clock, GrimAge, and DunedinPACE. These clocks are among the most validated methods for estimating biological age.