Your birth year tells one story. Your biology tells another. Answer nine questions to estimate how old your body actually is — and where to reclaim the most years.
Hours of sleep per night
Exercise days per week
VO₂ max estimate
VO₂ max is a measure of aerobic fitness. Many smartwatches estimate it. Use "Average" if unsure.
Typical stress level
Diet quality
Poor = mostly processed foods. Excellent = whole foods, vegetables, minimal sugar.
Daily sunlight exposure
Current smoker?
Alcohol consumption
Biological Age vs Chronological Age
Why your biological age matters more than the number on your birth certificate
The 12 Hallmarks of Ageing
The science behind why we age and what we can do about it
Epigenetic Clocks Explained
How DNA methylation patterns reveal your biological age
Senolytics: Clearing Ageing Cells
The emerging science of removing senescent cells to slow ageing
Biological age measures how old your body functions at a cellular and molecular level, which often diverges significantly from your chronological age — the number of years since you were born. Two people who are both 45 years old can have biological ages that differ by a decade or more depending on their lifestyle, genetics, and environment. Research from epigenetic clock studies by Steve Horvath at UCLA demonstrated that biological age calculated from DNA methylation patterns predicts mortality and disease risk more accurately than chronological age across a wide range of conditions.
The gap between biological and chronological age is not fixed. Longitudinal studies tracking the same individuals over time show that biological age can increase faster than the calendar in people with poor sleep, chronic stress, sedentary behaviour, and ultra-processed diets — and can slow, or even reverse, in response to targeted interventions. This plasticity is what makes biological age a clinically actionable metric rather than just a curiosity.
This tool estimates biological age using a weighted model built on lifestyle inputs validated in longevity epidemiology. Sleep quality is one of the strongest inputs: the Walker Lab at UC Berkeley has documented that consistently sleeping fewer than 7 hours per night accelerates biological ageing markers including telomere attrition and inflammatory cytokine levels. VO2 max, the body's maximal oxygen uptake capacity, is the single strongest predictor of all-cause mortality identified in any large prospective study — outperforming blood pressure, lipid levels, and body weight. The calculator combines these with resting heart rate, stress levels, dietary quality, and social connection data, all of which have independent associations with biological age markers in cohort studies.
The result is an educational estimate, not a clinical diagnosis. It reflects the same inputs used in research settings, but without direct biomarker measurements such as blood epigenetic clocks (Horvath, GrimAge, DunedinPACE), telomere length assays, or glucose variability tracking. Think of your score as a directional signal: it tells you which modifiable factors are likely accelerating or decelerating your biological clock.
Sleep has an outsized effect on biological age estimates because it drives cellular repair, autophagy (the clearance of damaged proteins), and hormonal rhythms that regulate inflammation. A consistent sleep duration of 7–9 hours with good quality (minimal waking, regular bedtime) is associated with the lowest biological age scores. Exercise, particularly aerobic exercise that elevates VO2 max, is the most potent anti-ageing intervention identified in the literature: a 2022 study in the Journal of the American College of Cardiology found that high cardiorespiratory fitness was associated with a 14–17% reduction in mortality compared to average fitness, independent of all other risk factors. Diet quality — particularly higher fruit, vegetable, and whole grain intake relative to ultra-processed food — affects biological age through its influence on gut microbiome diversity, systemic inflammation, and metabolic flexibility.
Go Deeper
Our comprehensive guide covers how biological age is measured, what drives the gap between biological and chronological age, and evidence-based interventions to reduce it.
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