Methodology

How the BioAge.io calculator works, and what the research shows

Short version. BioAge.io starts with your age and adds or subtracts years for six habits: sleep, exercise, diet, stress, smoking and alcohol. The years are the site's own simplified weights. They are not measured in your body, and they are not taken from one study. The research behind each habit points in the same direction as the calculator, but the studies measure different things (death rates, life expectancy, or lab-based "ageing clocks"), not "years of biological age" from a questionnaire. Treat the result as a snapshot of your habits, not a medical measurement.

Last reviewed 2026-10-15. Not medically reviewed.

The formula, exactly as the calculator runs

The result is your age plus the sum of these adjustments, rounded to one decimal.

Worked example (the site's own): a 50-year-old who sleeps 7.5 hours (−1), exercises 5+ days a week (−3), eats Mediterranean-style (−2.5), has low stress (−1.5), has never smoked (−1) and drinks within low-risk guidelines (0) gets 50 − 9 = 41.

What the research shows, habit by habit

For each habit: the direction the research points, what the study actually measured, and its limit. None of these studies gives "years of biological age" for a questionnaire answer, so none of them supports the exact numbers in the table above.

Sleep

Direction: both short and long sleep are linked to older biological age; the lowest values are around 6.4 to 7.8 hours.

Study: "Sleep chart of biological ageing clocks in middle and late life", Nature, published 13 May 2026. It relates self-reported sleep duration to 23 biological-age "clocks" built from brain imaging, blood proteins and metabolites in the UK Biobank (ages 37 to 84). It found a U-shaped pattern, with the lowest age gaps between 6.4 and 7.8 hours depending on organ and sex, and short (under 6 hours) and long (over 8 hours) sleep, compared with 6 to 8 hours, linked to higher risk of disease and death.

Limit: observational and self-reported: it cannot prove that changing your sleep changes your biological age. It does not provide "years per hour".

Our assessment: the calculator follows the same U-shape: 7 to 8 hours −1, and less than 6 or more than 8 hours +1 each. These are our own weights, not figures from the study. We keep them small because how much sleep people need varies from person to person.

Exercise

Direction: more regular physical activity is linked to a younger-looking biology.

Study 1: the DAMA trial (Fiorito et al., Aging Cell, 2021): a randomised 24-month trial in 219 healthy postmenopausal women in Florence, Italy. The physical-activity group had a lower "epigenetic mutation load" than the control group (difference −2.06, 95% CI −2.84 to −1.28), but no significant effect on the DNAmGrimAge clock.

Study 2: "The Association of Physical Activity Behaviors and Patterns With Aging Acceleration: Evidence From the UK Biobank" (J Gerontol A Biol Sci Med Sci, 2023): 284 479 participants. Strenuous sports and other leisure exercise were associated with lower aging acceleration (a measure based on phenotypic age and telomere length).

Limit: one trial in older women; the other study is observational. Neither gives a figure for "years for 3-4 days a week".

Diet

Direction: better diet quality is linked to slower biological ageing and lower death rates.

Study 1: the DAMA trial (above): the dietary intervention slowed the DNAmGrimAge clock by 0.66 years versus control over 24 months (95% CI −1.15 to −0.17, p = 0.01). It did not significantly change epigenetic mutation load.

Study 2: Li et al., Circulation, 2018, using the Nurses' Health Study (78 865 women) and the Health Professionals Follow-up Study (44 354 men): a high diet-quality score (upper 40%) was one of five low-risk lifestyle factors. People with all five had a 74% lower risk of death from any cause than people with none (hazard ratio 0.26, 95% CI 0.22 to 0.31).

Limit: the calculator's −2.5 years for a Mediterranean-style diet is larger than the only randomised result above (−0.66 years). The Circulation study measures deaths, not biological age.

Stress

No study cited. The stress weights (+2 for 9-10, −1.5 for 1-3) are the site's own judgement, and this page does not claim a study supports them. Self-rated 1-10 stress is also subjective.

Smoking

Direction: never smoking is linked to longer life.

Study: Li et al., Circulation, 2018 (above): "never smoking" was one of the five low-risk lifestyle factors.

Our assessment: never −1, used to but quit 0, smokes now +3. These are our own weights, not figures from a study. The study does not give years of biological age, and its summary does not define a separate group for people who have quit; scoring them 0 is our own choice.

Alcohol

Direction: drinking above low-risk levels points the wrong way.

Study: Li et al., Circulation, 2018 (above): "moderate alcohol intake" was counted as one of the five low-risk lifestyle factors.

Our assessment: none 0, within low-risk guidelines 0, more than that +2. These are our own weights, not figures from a study. We deliberately score no alcohol and low-risk drinking the same, so the calculator never rewards drinking. We do not give a limit in grams because guidelines differ between countries; follow the guidelines where you live.

Limits, and what the calculator is not

• It is an educational lifestyle estimate. It is not a medical device, diagnosis or medical advice.
• It does not measure your cells. Lab approaches (blood-marker formulas such as PhenoAge, and DNA-methylation clocks) measure biology directly, and even they disagree with each other. See How to calculate your biological age.
• The studies above show associations (and, in one case, a randomised trial in one group of women). They do not prove that the exact years in the table will happen for you.
• Your answers stay in your browser: the calculator's script makes no network requests.

Sources

1. Li Y et al. Impact of Healthy Lifestyle Factors on Life Expectancies in the US Population. Circulation, 2018. ahajournals.org
2. Fiorito G et al. DNA methylation-based biomarkers of aging were slowed down in a two-year diet and physical activity intervention trial: the DAMA study. Aging Cell, 2021. PMC8520727
3. Sleep chart of biological ageing clocks in middle and late life. Nature, 13 May 2026. nature.com
4. The Association of Physical Activity Behaviors and Patterns With Aging Acceleration: Evidence From the UK Biobank. J Gerontol A Biol Sci Med Sci, 2023. PMC10172984

Changelog

2026-10-15 Added questions on smoking and alcohol (our own weights). Sleep now follows a U-shape: less than 6 and more than 8 hours each add 1 year (short sleep was +2, long sleep was 0).

2026-10-10 First version.