100% Free

    Free Biological Age Calculator

    Estimate your biological age in 2 minutes — no signup, no blood test, no email required.

    Units
    Basics
    Body & Cardio
    Movement
    Sleep
    3— neutral
    12345
    Lifestyle
    3— mixed
    12345
    3— moderate
    12345

    How this calculator works

    Your biological age estimate is your chronological age plus the signed sum of five dimension deltas. Each dimension translates an underlying body of mortality research into a number of years to add or subtract.

    Formula: BiologicalAge = ChronologicalAge + Σ(Δbody composition, Δcardiovascular fitness, Δstrength & movement, Δsleep & recovery, Δlifestyle habits). The result is clamped between your chronological age minus 15 years and your chronological age plus 20 years to avoid implausible extremes.

    Your data never leaves your browser. There is no signup, no email, no analytics on the inputs you type.

    What we measure, dimension by dimension

    1. Body Composition

    We use BMI (derived from your height and weight) and waist circumference. BMI follows a U-shaped relationship with mortality — both underweight and obese ranges add risk — while waist circumference independently predicts metabolic and cardiovascular outcomes above and beyond BMI.

    Cutoffs follow WHO criteria for waist circumference (>94 cm in men, >80 cm in women is the first risk threshold; >102 cm and >88 cm respectively are the high-risk threshold).

    2. Cardiovascular Fitness

    We estimate your VO₂max from age, sex, waist circumference, resting heart rate, and a Personal Activity Rating derived from your reported cardio sessions, duration, and intensity. The formula is the non-exercise VO₂peak regression published by Nes et al. (2011) from the Norwegian HUNT3 cohort (n ≈ 5,000).

    Your estimated VO₂max is compared to the age- and sex-adjusted median (Cooper Institute / ACSM norms), and each mL/kg/min above or below the median adjusts your biological age by 0.4 years.

    A separate small penalty is applied for resting heart rate above 65 bpm, reflecting Aune et al. (2017) which found a 17% increase in all-cause mortality per 10-bpm increase in resting heart rate.

    3. Strength & Movement

    Three inputs: strength sessions per week, daily steps, and daily sedentary hours. Resistance training 2–3 times per week reduces all-cause mortality by approximately 21% (Saeidifard 2019). Daily step count has a clear dose–response relationship with mortality through about 10,000 steps (Paluch 2022). Prolonged sedentary time independently increases mortality risk beyond what exercise can fully offset (Patterson 2018).

    4. Sleep & Recovery

    Sleep duration follows a U-shape: 7–8 hours is associated with the lowest mortality, while <6 or >9 hours both increase risk (Yin 2017). Sleep regularity — measured here as a 1–5 self-rating of how consistent your bedtime and wake time are — is a powerful independent predictor: Windred et al. (2024, SLEEP) found regularity was a stronger predictor of mortality than duration.

    5. Lifestyle Habits

    Smoking is the largest single modifiable lever in the calculator. Doll et al. (2004), in 50 years of follow-up on British doctors, found that lifelong smokers die approximately 10 years earlier than non-smokers, and that those who quit by age 40 recover most of those years.

    Alcohol intake follows a near-monotonic risk curve in the GBD 2016 Alcohol Collaborators meta-analysis (Lancet 2018), with the minimum-risk dose being zero.

    Diet quality is captured by a 1–5 self-rating, anchored to the Mediterranean dietary pattern (Estruch 2018, NEJM).

    Chronic psychological stress (Cohen 2007) is captured by a 1–5 self-rating.

    How accurate is this?

    Less accurate than a blood test, more accurate than a vibe-check. Our estimate is bounded by three real limitations: self-report bias (especially for stress, diet, and sleep), the fact that we translate hazard ratios from published cohorts into 'years' using best-effort approximations, and the fact that we don't measure molecular markers directly.

    The number we show is an estimate — we deliberately don't display a fixed ±X years next to it, because the uncertainty depends on which inputs you can answer most accurately and on how each dimension contributes for your specific profile. Real epigenetic clocks (PhenoAge, GrimAge, DunedinPACE) require a blood draw or methylation array and cost $200–$500 — they are more accurate but not free.

    Most of our cited studies were conducted in predominantly European-ancestry cohorts. If you are of non-European ancestry, the absolute coefficients may be off by a few years; the relative ranking across dimensions remains informative.

    What "biological age" actually means

    Biological age is an estimate of how old your body looks at the molecular, physiological, or functional level — independent of how many birthdays you've had. The field recognizes three generations of biological-age algorithms.

    First-generation clocks (Horvath 2013, Hannum 2013) were trained to predict chronological age from DNA methylation patterns. They're very accurate at guessing age, but only modest at predicting mortality.

    Second-generation clocks (PhenoAge, GrimAge) are trained directly on mortality and clinical outcomes — they predict who is on track to live longer.

    Third-generation clocks like DunedinPACE measure the pace of aging — how fast you're aging right now, rather than an accumulated number — and are the most responsive to short-term interventions.

    This calculator is a self-report composite, conceptually closer to second-generation: it weighs each input by its association with mortality and healthspan.

    References

    Frequently asked questions

    This calculator provides an educational estimate, not a medical diagnosis. Talk to a clinician about anything you're worried about.