Free Tool
⏱ Biological Age Assessment

How old is your body,
really?

Your chronological age tells you how many years you've lived. Your biological age tells you how fast you're living them. Answer 8 evidence-based domains and get your personalized assessment in under 4 minutes.

Have recent blood work? Calculate your PhenoAge from nine lab values →

✓ Based on peer-reviewed research ✓ 8 research-informed domains ✓ No sign-up required ✓ Free forever
Methodology

A lifestyle-based estimate. The domain weights draw on research on fitness, metabolic health, sleep, strength, stress and social connection (sources below). It does not use the PhenoAge formula, which needs nine blood tests, and it has not been validated against measured biological age.

Levine 2018 Myers NEJM Cappuccio 2010
Section 1 of 8

The Basics

Your chronological age and sex are the baseline against which your biological age is calculated. These are fixed inputs — everything else you can change.

Used as the baseline. Your biological age will be calculated relative to this number — younger means you're aging slower than your peers, older means faster.

Years old (must be 18–100)

Sex affects reference ranges for nearly every longevity biomarker — from optimal VO₂max to cardiovascular risk thresholds. We use it only for scoring accuracy.

Section 2 of 8

Cardiovascular Fitness

VO₂max — your maximal oxygen uptake — is the single most powerful predictor of longevity in the scientific literature, surpassing smoking status, diabetes, and hypertension in predictive value.

Why this matters: In a 2018 study of 122,007 patients who had treadmill tests, the least fit had about five times the risk of death of the most fit, an association comparable to or stronger than traditional risk factors.

Be honest — this is the highest-impact domain in the assessment.

A lower resting heart rate reflects greater cardiovascular efficiency. Elite endurance athletes often sit at 40–50 bpm; optimal longevity range is below 60 bpm.

70 bpm
40 bpm (elite) 70 bpm (average) 100 bpm (high)
Section 3 of 8

Metabolic Health

Only 6.8% of US adults had optimal cardiometabolic health across five measures in a 2022 analysis of national survey data. Metabolic dysfunction is the upstream driver of cardiovascular disease, dementia, and accelerated aging.

Key insight: Fasting glucose and HbA1c, even within "normal" lab ranges, exist on a continuous risk curve. Optimal longevity glucose is 70–85 mg/dL, not the lab "normal" of up to 99 mg/dL.

Diet is the primary driver of metabolic health. We use this as a proxy for fasting glucose, insulin sensitivity, and inflammatory load.

These conditions directly indicate metabolic dysfunction and accelerate biological aging through glycation, inflammation, and mitochondrial impairment.

Section 4 of 8

Sleep Quality & Duration

Sleep is not optional recovery — it is the primary mechanism by which the glymphatic system clears amyloid-β from the brain, growth hormone is secreted for tissue repair, and immune memory is consolidated.

The U-shaped curve: Both short sleep (<6 hours) and long sleep (>9 hours) are associated with higher all-cause mortality in a meta-analysis of 1.4 million people. The optimal window is 7–9 hours with consistent timing.
7 hrs
3 hrs 7 hrs (optimal) 11 hrs

Duration alone isn't enough — architecture matters. Disrupted sleep fails to deliver the deep slow-wave sleep needed for cellular repair and the REM sleep required for cognitive consolidation.

Section 5 of 8

Body Composition & Strength

Visceral fat — not total body weight — is the metabolically active tissue that drives inflammation, insulin resistance, and accelerated aging. Meanwhile, muscle mass is increasingly recognized as the primary organ of longevity.

Grip strength as a biomarker: A 2015 Lancet study of 140,000 people found that grip strength was a stronger predictor of cardiovascular mortality than blood pressure. Low muscle mass (sarcopenia) is associated with dramatically higher all-cause mortality and is now considered a longevity disease in its own right.

This is about fat distribution and muscle quality, not just weight. A person can have a "normal" BMI but high visceral fat — what's called "TOFI" (Thin Outside, Fat Inside).

Resistance training is the main proven way to rebuild muscle lost with age, and muscle-strengthening activity is associated with 10–17% lower all-cause mortality.

Section 6 of 8

Stress, Cortisol & Mental Health

Chronic psychological stress is not merely uncomfortable — it measurably accelerates epigenetic aging by activating the HPA axis, shortening telomeres, driving chronic inflammation, and impairing immune function.

Telomere connection: In a 2004 study by Elissa Epel and Elizabeth Blackburn (who later shared the 2009 Nobel Prize), women with the highest perceived stress had telomeres shorter by the equivalent of at least a decade of extra aging compared with low-stress women. Stress is a biological aging accelerant, not just a quality-of-life issue.

Mindfulness-Based Stress Reduction (MBSR) has the strongest RCT evidence — 8-week programs reduce perceived stress and anxiety; effects on biological aging markers are uncertain.

Section 7 of 8

Lifestyle & Habits

Smoking, alcohol, and social connection are among the most powerful lifestyle determinants of biological age. The effect sizes are large enough to meaningfully shift results in either direction.

Smoking is among the highest-impact modifiable risk factors for early death. Even 5–10 cigarettes/day produces meaningful harm.

No amount of alcohol is considered safe for cancer risk. US guidelines advise no more than one drink a day for women and two for men, and less is better. Heavy drinking accelerates brain aging and liver disease.

Section 8 of 8

Social Connection & Purpose

The science of longevity's most underrated domain. In a 2015 meta-analysis, social isolation was associated with 29% higher odds of death. Purpose and meaning in life predict slower biological aging independent of all other factors.

Blue Zone evidence: In all five Blue Zones — Okinawa, Sardinia, Nicoya, Ikaria, Loma Linda — strong social networks and a sense of purpose (Ikigai in Okinawa, Plan de Vida in Nicoya) were among the most consistent predictors of exceptional longevity, alongside plant-rich diets and natural daily movement.

Quality matters more than quantity. One or two deep relationships are more protective than dozens of superficial ones. Loneliness is not about being alone — it's about feeling disconnected.

In a 2019 study of 6,985 US adults over 50, those with the weakest sense of purpose had 2.43 times the risk of death of those with the strongest over about four years.

Analyzing your longevity profile…

Scoring your answers across 8 research-informed domains.

🫀 Scoring cardiovascular fitness
⚡ Calculating metabolic health score
😴 Weighting sleep quality & duration
💪 Assessing body composition
🧠 Factoring stress & resilience
🚭 Applying lifestyle modifiers
🤝 Incorporating social & purpose
📊 Generating your biological age
Your Result

Your estimated biological age

—yrs

Domain Breakdown

How each area contributes to your biological age

What's driving your biological age

Your Personalized Action Plan

Based on your domain scores, these are the highest-leverage changes you can make. The interventions with the strongest evidence and largest effect size are listed first.

ℹ️

Medical Disclaimer: This calculator provides an educational estimate based on self-reported lifestyle factors and population-level research. It is not a medical diagnosis and cannot replace clinical biomarker testing (bloodwork, VO₂max testing, DEXA scan, epigenetic clocks such as TruMe, or glycan-based tests such as GlycanAge). For precision biological age testing, consult your physician or request the Levine PhenoAge panel, which uses actual biomarkers. Results reflect general trends in population research, not your individual physiology.

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PhenoAge calculator: biological age from nine blood tests

The questionnaire above is a lifestyle estimate. If you have recent blood work, this calculator applies the published Phenotypic Age model (Levine et al., 2018): nine routine lab values plus your age, weighted by how strongly each predicted 10-year mortality in a large US national survey, then expressed in years (sources 3 and 16 below).

Use values from the same blood draw, ideally when you are well: an infection raises CRP and white cells. Units are US conventional; the calculator converts them to the units in the paper (albumin g/L, creatinine µmol/L, glucose mmol/L, CRP mg/dL). The model was built in adults 20 and over. It estimates risk at the population level and is not a diagnosis.

Scientific Methodology

How This Calculator Works — and What It Can't Tell You

This tool uses a weighted scoring model across 8 research-informed domains. Each domain is grounded in peer-reviewed research, with weights assigned proportional to effect size in mortality and aging studies. Here's exactly what we measure and why.

🫀
Cardiovascular Fitness (25% weight)
The single highest-weighted domain, reflecting its disproportionate effect on longevity. Based on VO₂max-mortality curves from Myers et al. (NEJM 2002) and the 122,000-patient Mandsager study (JAMA 2018) showing fitness to be a strong predictor of mortality.
Myers et al., NEJM 2002 · Mandsager et al., JAMA Netw Open 2018
⚡
Metabolic Health (20% weight)
Informed by research linking blood sugar and other metabolic markers to aging and mortality (fasting glucose is one of the nine blood markers in Levine's PhenoAge). Only 6.8% of US adults had optimal cardiometabolic health in a 2022 national analysis.
Levine et al., Aging 2018 · O'Hearn et al., JACC 2022
😴
Sleep Duration & Quality (15% weight)
Based on the U-shaped sleep-mortality relationship documented by Cappuccio et al. (Sleep 2010). Scoring penalizes both below 6 hours and above 9 hours.
Cappuccio et al., Sleep 2010
💪
Body Composition & Strength (15% weight)
Informed by the Leong Lancet study (2015) on grip strength as mortality predictor, NHANES body composition norms, and Srikanthan's findings that muscle mass index independently predicts all-cause mortality independent of fat mass.
Leong et al., Lancet 2015 · Srikanthan et al., AJMED 2014
🧠
Stress & Mental Health (10% weight)
Grounded in Epel and Blackburn's telomere research (2004–2009) connecting chronic stress to accelerated epigenetic aging, and cortisol's documented role in hippocampal damage, immune suppression, and visceral fat accumulation.
Epel et al., PNAS 2004 · Blackburn & Epel, Telomere Effect 2017
🚭
Lifestyle Factors (10% weight)
Smoking penalties reflect smoking's large effect on mortality. Alcohol scoring based on GBD 2016 data and the large-scale UK Biobank findings on alcohol's dose-dependent aging effects.
GBD Collaborators, Lancet 2018 · UK Biobank 2022
🤝
Social Connection & Purpose (5% weight)
Based on Holt-Lunstad's meta-analyses (PLoS Med 2010; Perspect Psychol Sci 2015, which found 29% higher odds of death with social isolation) and a 2019 JAMA Network Open study linking stronger purpose in life to lower mortality.
Holt-Lunstad et al., PLoS Med 2010 and Perspect Psychol Sci 2015 · Alimujiang et al., JAMA Netw Open 2019
📊
Baseline Demographics (calibration)
Chronological age and sex serve as the calibration baseline. All domain scores are normalized against NHANES age- and sex-specific norms to produce a relative biological age estimate, not an absolute prediction.
NHANES 2017–2020 reference data

Important Limitations to Understand

This is an unvalidated lifestyle estimate, not a biological age measurement. True biological age requires laboratory testing — epigenetic clocks (DNA methylation), GlycanAge, TruMe, or the full Levine PhenoAge bloodwork panel.
Self-reported data introduces response bias. People tend to overestimate exercise frequency and underestimate alcohol consumption. Our scoring weights account for this somewhat, but cannot fully correct for it.
This tool captures modifiable lifestyle factors only. Twin studies estimated that genes explain about a quarter of the variation in lifespan (Hjelmborg et al., 2006), but a 2018 analysis of hundreds of millions of family-tree records put the true figure well below 10%. Most of the rest reflects lifestyle, environment and chance, only some of which this tool assesses.
Results should be interpreted as a directional guide, not a precise number. A result of "42 biological years" when you're 45 chronologically is only a rough signal: the tool has not been validated, so its margin of error is unknown.
This calculator is not a substitute for medical care. Several domains (metabolic health, cardiovascular fitness) should ultimately be confirmed with actual biomarker testing and clinical assessment.
Primary Sources & Citations
Myers J, Prakash M, Froelicher V, Do D, Partington S, Atwood JE. Exercise capacity and mortality among men referred for exercise testing. N Engl J Med. 2002;346(11):793-801.
Mandsager K, Harb S, Cremer P, Phelan D, Nissen SE, Jaber W. Association of cardiorespiratory fitness with long-term mortality among adults undergoing exercise treadmill testing. JAMA Netw Open. 2018;1(6):e183605.
Levine ME, Lu AT, Quach A, et al. An epigenetic biomarker of aging for lifespan and healthspan. Aging (Albany NY). 2018;10(4):573-591.
O'Hearn M, Lauren BN, Wong JB, Kim DD, Mozaffarian D. Trends and disparities in cardiometabolic health among U.S. adults, 1999-2018. J Am Coll Cardiol. 2022;80(2):138-151. PubMed
Cappuccio FP, D'Elia L, Strazzullo P, Miller MA. Sleep duration and all-cause mortality: a systematic review and meta-analysis of prospective studies. Sleep. 2010;33(5):585-592.
Leong DP, Teo KK, Rangarajan S, et al. Prognostic value of grip strength: findings from the Prospective Urban Rural Epidemiology (PURE) study. Lancet. 2015;386(9990):266-273.
Epel ES, Blackburn EH, Lin J, et al. Accelerated telomere shortening in response to life stress. Proc Natl Acad Sci U S A. 2004;101(49):17312-17315.
Holt-Lunstad J, Smith TB, Layton JB. Social relationships and mortality risk: a meta-analytic review. PLoS Med. 2010;7(7):e1000316.
Alimujiang A, Wiensch A, Boss J, et al. Association between life purpose and mortality among US adults older than 50 years. JAMA Netw Open. 2019;2(5):e194270.
Srikanthan P, Karlamangla AS. Muscle mass index as a predictor of longevity in older adults. Am J Med. 2014;127(6):547-553.
GBD 2016 Alcohol Collaborators. Alcohol use and burden for 195 countries and territories, 1990–2016. Lancet. 2018;392(10152):1015-1035.
Hjelmborg JV, Iachine I, Skytthe A, et al. Genetic influence on human lifespan and longevity. Hum Genet. 2006;119(3):312-321.
Holt-Lunstad J, et al. Loneliness and social isolation as risk factors for mortality: a meta-analytic review. Perspect Psychol Sci. 2015. PubMed
Ruby JG, et al. Estimates of the Heritability of Human Longevity Are Substantially Inflated due to Assortative Mating. Genetics. 2018. PubMed
Momma H, et al. Muscle-strengthening activities are associated with lower risk and mortality in major non-communicable diseases: a systematic review and meta-analysis of cohort studies. Br J Sports Med. 2022. PubMed
Liu Z, Kuo PL, Horvath S, Crimmins E, Ferrucci L, Levine M. A new aging measure captures morbidity and mortality risk across diverse subpopulations from NHANES IV: A cohort study. PLoS Med. 2018. PubMed
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