The Biological Organ Age Test: Calculate Your Heart, Brain, and Metabolic Age

An organ age test estimates how old a specific organ, such as your heart, brain, or kidneys, appears biologically compared with your chronological age. A heart age calculator uses blood pressure, cholesterol, smoking, and diabetes; a metabolic age calculator compares your BMR with age-group averages; and a brain age test uses MRI or cognitive scores.

Unlike a whole-body biological age test, it shows which organ may be ageing faster, and a large gap can signal higher disease risk.

Metabolic age compares your BMR with age-group averages. Brain age is measured by MRI or cognitive tests. A gap between organ age and your age in years can signal higher health risk.

Your body does not necessarily age at one uniform speed. Research from Stanford-led scientists found that different organs can show markedly different rates of biological ageing within the same person.

If you want to understand your biological ageing, assess organ health, or make sense of an organ age result, this guide explains how heart, metabolic, and brain age are estimated, how biological age differs from chronological age, how lifestyle and disease can shift organ ageing, how accurate these tests are, and how to use the results to guide prevention and conversations with a healthcare professional.

Chronological age is the number of years you have lived, while biological age describes measurable features associated with how your body is ageing.

The difference between chronological vs biological age is that chronological age is fixed by your date of birth, whereas biological-age estimates vary according to the markers and algorithm used.

Biological-age estimates can use blood biomarkers, physical function, DNA methylation patterns, organ-function measurements, or combinations of these data. Importantly, there is no single universally accepted test that captures every aspect of biological ageing.

Chronological age simply measures how many years have passed since your birth. It is fixed and objective and is used throughout medical guidelines to determine age-related screening recommendations and disease-risk thresholds.

It does not directly tell you how well your organs are functioning. Two people of the same chronological age can therefore have very different cardiovascular, metabolic, cognitive, or physical health profiles.

Biological age attempts to describe aspects of ageing that are not captured by the calendar alone. Depending on the method, it may incorporate blood biomarkers, clinical measurements, DNA methylation, proteomic signatures, physical function, or imaging.

Epigenetic clocks, for example, use patterns of DNA methylation to estimate age-related biological characteristics, but different clocks measure different aspects of ageing and are not interchangeable.

An age gap is generally calculated by subtracting chronological age from an estimated biological or organ age. A positive gap means the tested measure estimates an older age than your chronological age, while a negative gap means it estimates a younger age.

However, a negative result should not automatically be interpreted as proof of better health because each test has its own algorithm, reference population, measurement error, and biological limitations.

An organ age test attempts to estimate how old a particular organ appears biologically compared with people of the same chronological age. Research methods can use organ-specific blood proteins, imaging data, physiological measurements, or clinical risk factors.

Commercial "organ age" products may use much simpler calculations, so the term does not always refer to the same type of measurement.

Research-grade organ-age models can analyse proteins circulating in the blood that are associated with particular tissues or organs. Imaging can provide structural information, while clinical tests such as blood pressure, eGFR, liver enzymes, or spirometry provide functional information about specific organs.

These approaches answer different questions and should not be treated as equivalent ways of measuring an organ's biological age.

A major advance came from Oh et al., whose study “Organ aging signatures in the plasma proteome track health and disease” was published in Nature in 2023. Researchers analysed 4,979 plasma proteins in 5,676 adults and developed machine-learning models to estimate biological age for 11 organs.

The study found that 18.4% of participants had a highly organ-specific accelerated-age pattern, while about 1.7% showed accelerated ageing across multiple organs. Among participants without active disease or clinically abnormal biomarkers at baseline, each 4.1-year increase in heart age, equivalent to one standard deviation in the study's heart-age gap, was associated with an almost 2.5-fold higher risk of heart failure over 15 years. The researchers also reported 15%–50% higher all-cause mortality risk for a one-standard-deviation increase in age gap across several organs.

A follow-up study published in Nature Medicine in 2025 analysed 2,916 plasma proteins from 44,498 UK Biobank participants and estimated the biological age of 11 organs. Over up to 17 years of follow-up, organ-age estimates were associated with future disease incidence, including heart failure, COPD, type 2 diabetes, and Alzheimer's disease.

The 2025 analysis reported that a one-standard-deviation increase in heart-age gap was associated with a hazard ratio of 1.83 for future heart failure, while brain-age gap was associated with a hazard ratio of 1.80 for Alzheimer's disease. Lung-age gap was associated with a 1.39 hazard ratio for COPD, and pancreas-age gap with a 1.80 hazard ratio for chronic kidney disease.

These results strengthen the research evidence for organ-specific ageing models, but they do not establish that a consumer organ-age test can diagnose disease or predict an individual's future disease with the same effect sizes.

A whole-body biological-age test attempts to summarize ageing across the body, whereas an organ-age test focuses on a particular tissue or physiological system.

DNA-methylation clocks are one example of whole-body or tissue-specific molecular ageing measures, while plasma-protein models can estimate the age of individual organs. Neither approach should be interpreted as a complete measurement of "how healthy" a person is because ageing is multidimensional.

Organs are exposed to different combinations of genetic factors, blood flow, metabolic demands, inflammation, environmental exposures, and disease processes.

The Stanford research demonstrates that measurable differences in organ ageing can occur even among people of similar chronological age.

This helps explain why one person may have relatively preserved cardiovascular function but reduced kidney function, or vice versa.

Genes influence susceptibility to many age-related diseases, but ageing is not determined by genetics alone. Over time, cells accumulate molecular and structural changes involving DNA regulation, proteins, mitochondria, inflammation, and tissue repair.

The interaction between inherited biology and environmental exposures helps create differences in how individual organs age.

Many factors in lifestyle can place different kinds of stress on different organs. Smoking is strongly associated with cardiovascular and lung disease, while alcohol can contribute to liver injury and other health problems; poor diet, physical inactivity, and excess body weight can influence metabolic and cardiovascular health.

A healthy lifestyle with a balanced diet, better nutrition, regular exercise, and quality sleep supports healthier ageing. Diets high in processed foods can worsen metabolic health, while someone who exercises regularly may improve it.

WHO recommends regular physical activity and identifies tobacco and harmful alcohol use among important preventable health risks.

Long-standing conditions such as hypertension, diabetes, fatty liver disease, and chronic kidney disease can affect particular organs more strongly than others.

For example, high blood pressure can damage blood vessels and increase cardiovascular and brain-related risks, while diabetes can affect the kidneys, eyes, nerves, and cardiovascular system. Managing these conditions is therefore more useful than focusing only on an age score.

An unusually high organ-age estimate may identify a health area that deserves closer assessment, particularly when it agrees with established clinical measurements.

The 2023 Stanford study found associations between accelerated organ ageing and disease-specific outcomes, while the 2025 UK Biobank analysis found associations with several future diseases.

These are population-level research findings and should not be interpreted as an individual diagnosis or a guarantee that disease will occur.

Heart age is a way of translating cardiovascular risk factors into an easier-to-understand age-based estimate. It generally uses established cardiovascular risk equations rather than directly measuring the physical age of the heart.

The American Heart Association's 2023 PREVENT equations are a newer cardiovascular risk framework that estimates 10-year and 30-year risk of total cardiovascular disease, including ASCVD and heart failure, for eligible adults aged 30–79 without known cardiovascular disease.

The AHA PREVENT calculator combines cardiovascular, kidney, and metabolic health factors. Required inputs include age, sex, systolic blood pressure, total and HDL cholesterol, kidney function, BMI, diabetes status, smoking status, and relevant medication use. Optional inputs can include HbA1c, urine albumin-to-creatinine ratio, and a social deprivation index.

PREVENT can also translate cardiovascular risk into an estimated “heart age” through its PREVENT-Age measure. This is still a risk-based estimate rather than a direct measurement of the biological age or physical condition of the heart.

Depending on the calculator, inputs can include chronological age, sex, systolic blood pressure, blood-pressure treatment, total cholesterol, HDL cholesterol, smoking status, diabetes, and sometimes BMI.

The Framingham Heart Study describes cardiovascular risk models using many of these variables, while contemporary ASCVD calculators use a defined set of demographic and clinical factors.

A heart-age calculation starts with a cardiovascular risk equation and compares the individual's estimated risk with reference risk levels for people of different ages.

Framingham-based models and the ACC/AHA ASCVD approach use combinations of age, sex, cholesterol, blood pressure, smoking, diabetes, and treatment variables. The exact heart-age result can therefore differ between calculators because the underlying population, equation, and definition of "heart age" may differ.

If your calculated heart age is above your chronological age, it generally means that the risk-factor profile resembles that of an older reference population.

A lower heart age indicates a lower estimated risk relative to the calculator's reference group, but it does not prove that your arteries or heart are biologically younger.

Discuss unexpectedly high results or major cardiovascular risk factors with a healthcare professional rather than relying on the number alone.

Imagine a 55-year-old person whose cardiovascular risk factors produce a PREVENT-Age estimate of 62 years. The calculated heart age would therefore be 7 years higher than the chronological age (62 − 55 = 7 years).

This does not mean that the person's anatomical heart is literally 62 years old. It means that the person's estimated cardiovascular risk corresponds to the reference risk represented by that heart-age calculation.

The result should be interpreted alongside blood pressure, cholesterol, diabetes status, kidney function, smoking status, family history, and other clinically relevant factors. Use the official AHA PREVENT calculator for an actual individual calculation rather than estimating a PREVENT score from a simplified formula.

"Metabolic age" is mainly a wellness concept rather than a standardized clinical diagnosis. It commonly compares an individual's estimated resting energy expenditure or body-composition profile with population averages for different age groups.

Because metabolism depends strongly on body size, muscle mass, sex, age, and other factors, a metabolic-age number should be treated as an estimate rather than a direct measurement of metabolic health.

Metabolic age usually describes the age group whose average estimated basal or resting metabolic rate is closest to yours, with metabolic age calculated by comparing your basal metabolic rate with the average BMR for an age group.

It does not directly measure insulin sensitivity, blood glucose control, liver health, cardiovascular risk, or thyroid function, and this comparison can differ from your actual age or real age.

A person can have a "young" metabolic age on a smart scale while still having high blood pressure, abnormal glucose, or abnormal cholesterol.

The Mifflin-St Jeor equation is a commonly used predictive equation for resting energy expenditure. It defines basal metabolic rate as the minimum calories the body burns at rest to maintain vital functions.

The original 1990 study developed the equation using age, weight, height, and sex, but the calculated value remains an estimate rather than a direct measurement obtained by indirect calorimetry.

For men:

BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5

For women:

BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161

The Mifflin-St Jeor equations were published in 1990 and are commonly used to estimate resting energy expenditure. The result is an estimate rather than a direct measurement of BMR.

Because BMR depends on sex, height and body weight as well as age, there is no single universal BMR value for each age. For a practical worked example, the table below holds body weight at 65 kg and height at 160 cm and recalculates the Mifflin-St Jeor estimate at different ages. This is an illustrative reference table, not a clinical population reference range.

Important: This table demonstrates how the calculation works. It should not be presented as a standardized clinical “metabolic-age reference range.” There is no universally accepted clinical definition of metabolic age.

Identify the age group with the closest reference BMR. Because BMR changes continuously with age and varies with body size and composition, a metabolic age should be treated as a rough wellness estimate rather than a clinical measurement.

Treat the result as a wellness estimate rather than a diagnosis of metabolic health.

Smart scales generally use bioelectrical impedance analysis (BIA) to estimate body composition, and some also factor in body fat percentage when generating metabolic-age or related estimates, before applying proprietary algorithms.

Body fat can affect the estimate because it changes the body-composition assumptions built into those calculations. BIA measurements can be influenced by hydration, food and beverage intake, recent physical activity, body position, temperature, and the specific device or prediction equation used.

For this reason, smart-scale metabolic age is better used for observing trends under consistent measurement conditions than as a precise medical measurement.

Blood tests and other blood markers provide more clinically actionable information about metabolic health than a single metabolic-age score. HbA1c reflects average blood glucose over roughly the previous two to three months, while lipid testing evaluates cholesterol and triglyceride-related cardiovascular risk.

Fasting glucose, and in selected situations fasting insulin, can provide additional metabolic information; thyroid testing may be appropriate when symptoms or clinical assessment suggest a thyroid disorder rather than simply because someone wants to calculate metabolic age, and calorie needs also vary with activity level in ways that metabolic age does not capture well.

Consider a broader health assessment with MyDiagnostics when you want to check measurable metabolic markers such as glucose, HbA1c, lipids, thyroid markers, and other routine health parameters rather than relying on a wellness age score alone. If results look abnormal, consult a healthcare professional for interpretation.

Brain age can refer to several different concepts, including MRI-derived brain age, cognitive performance scores, or research-based biological-age models.

These approaches do not measure the same thing. A brain-age result should therefore be interpreted as a measure of a particular feature of brain structure or function, not as a definitive statement about dementia risk or overall brain health.

MRI-based brain-age models use patterns in brain structure to estimate how closely an individual's scan resembles brains from people of different ages.

The National Institute on Aging (NIA), part of the U.S. National Institutes of Health (NIH), notes that MRI findings are used alongside other information in dementia assessment and that brain shrinkage on MRI alone does not establish a specific diagnosis.

Online tests may assess memory, attention, processing speed, reaction time, language, or other cognitive skills. They can provide a snapshot of performance but are affected by education, language, sleep, anxiety, practice effects, technology, and testing conditions.

They cannot diagnose dementia, Alzheimer's disease, or another neurological disorder; clinical diagnosis requires a broader assessment and, when appropriate, imaging or biomarkers.

Brain health is closely connected with cardiovascular and metabolic health. High blood pressure, diabetes, physical inactivity, smoking, harmful alcohol use, poor sleep, and hearing loss have all been associated with poorer brain health or increased dementia risk, although an individual risk factor does not determine whether a person will develop dementia.

NIA recommends managing conditions such as high blood pressure and diabetes, staying physically active, maintaining healthy habits, and addressing sensory problems such as hearing loss.

Individual organ function can often be assessed more reliably with established clinical tests than with a generic "organ age" calculator. Kidney, liver, and lung tests measure specific aspects of organ function and can help identify abnormalities that warrant further evaluation. These tests do not necessarily produce an "age," but they provide clinically interpretable information.

There is no universally accepted clinical "kidney age" equivalent to chronological age. Kidney health is commonly assessed using serum creatinine to calculate eGFR, with urine albumin testing providing additional information about kidney damage.

Because creatinine is influenced by factors such as muscle mass, healthcare professionals may use cystatin C alongside creatinine in selected situations to improve estimation.

Liver health is assessed using a combination of blood tests, medical history, physical examination, and sometimes imaging. Tests may include ALT, AST, alkaline phosphatase, bilirubin, albumin, and other markers depending on the clinical question.

Abnormal liver enzymes can indicate liver injury but do not by themselves identify the cause or provide a reliable "liver age."

"Lung age" is a simplified way of comparing spirometry measurements with expected values for people of different ages. Spirometry measures how much air you can exhale and how quickly you can exhale it, making it a clinically useful test of lung function.

An abnormal result requires interpretation in context and may lead to further testing rather than simply being labelled as an older lung age.

The accuracy of a biological-age test depends on what it measures, how the algorithm was developed, which population it was validated in, and how reproducible the measurement is.

A clinically established biomarker such as HbA1c or eGFR has a different purpose and validation pathway from a proprietary biological-age score. Even research-grade ageing clocks should not automatically be treated as established diagnostic tests for individuals.

Clinically validated tests measure defined physiological or pathological characteristics using standardized methods and reference ranges.

Wellness estimates may combine lifestyle information, body measurements, BIA data, or proprietary algorithms to create an easy-to-understand score. The latter can be useful for motivation or tracking but should not replace established screening or diagnostic testing.

At-home products can measure different things depending on the provider, including blood biomarkers, DNA methylation, inflammation-related markers, body composition, or lifestyle variables. Two products marketed as "biological age tests" may therefore produce very different results.

Before purchasing one, check exactly which biomarkers are measured, how the age score is calculated, whether the method has been independently validated, and whether the result has established clinical utility.

Choose laboratory or clinical testing when you want to investigate a specific health concern, an abnormal result, or a known risk factor.

For example, elevated blood pressure should be confirmed and managed clinically rather than translated into a heart-age score alone. Similarly, suspected diabetes, kidney disease, liver disease, or lung disease requires appropriate diagnostic testing rather than a wellness calculator.

There is no single intervention that can "reverse" the age of every organ. However, many established cardiovascular and healthy-ageing strategies improve modifiable risk factors that influence several organ systems simultaneously.

The American Heart Association's Life's Essential 8 focuses on diet, physical activity, nicotine exposure, sleep, weight, blood lipids, blood glucose, and blood pressure.

Blood pressure is one of the most important modifiable cardiovascular risk factors. Persistent hypertension can damage blood vessels and increase the risk of heart disease, stroke, kidney disease, and cognitive decline.

Monitoring blood pressure regularly and following individualized lifestyle or medication advice can therefore benefit multiple organ systems.

High levels of atherogenic cholesterol contribute to plaque formation and cardiovascular disease. Dietary improvements, physical activity, weight management when appropriate, and prescribed lipid-lowering medication can help manage cholesterol. The AHA includes blood lipids as one of its eight major measures of cardiovascular health.

Stopping smoking has cardiovascular and respiratory benefits at any age, and the CDC reports that cardiovascular risk falls after smoking cessation. WHO states that alcohol consumption carries health risks even at low levels, with risk influenced by the amount and pattern of consumption.

Avoiding tobacco and reducing or avoiding alcohol can therefore be important components of long-term organ-health protection.

WHO recommends that adults perform at least 150–300 minutes of moderate-intensity aerobic activity or 75–150 minutes of vigorous activity each week, alongside muscle-strengthening activities on at least two days per week.

Physical activity supports cardiovascular, metabolic, musculoskeletal, and cognitive health. Regular strength training can also help maintain muscle mass, which influences resting energy expenditure and body composition.

Quality sleep supports memory, attention, mood, metabolic health, and cardiovascular health. NIA notes that adults generally need around seven to nine hours of sleep, while research continues to investigate the relationship between sleep disturbances and cognitive ageing.

Managing chronic stress, maintaining a consistent sleep routine, and seeking medical assessment for persistent insomnia or suspected sleep apnea can support overall health.

The appropriate retesting interval depends on what you are measuring and your individual risk factors. A repeat blood pressure measurement may be appropriate much sooner than repeating a research-based biological-age test, while HbA1c may be repeated according to diabetes or prediabetes status and clinical advice.

If you are tracking a biological-age score, use the same test and similar conditions over time because switching methods can make changes difficult to interpret.

Instead of focusing on a single biological-age number, consider checking measurable markers that relate to important organ systems. A comprehensive assessment may include a lipid profile for cardiovascular risk, HbA1c or glucose for metabolic health, liver-function markers, kidney-function markers, and thyroid testing when clinically appropriate.

These results can be interpreted alongside blood pressure, BMI, lifestyle history, symptoms, and family history.

MyDiagnostics can be considered for convenient health testing when you want to measure relevant blood and organ-function markers rather than relying only on a biological-age calculator.

Instead of focusing on a single biological-age number, consider checking measurable markers that relate to important organ systems. A comprehensive assessment may include a lipid profile for cardiovascular risk, HbA1c or glucose for metabolic health, liver-function markers, kidney-function markers, and thyroid testing when clinically appropriate.

When choosing an at-home or laboratory health package, check the exact parameters included, sample type, laboratory accreditation, turnaround time, and whether medical interpretation or consultation is provided. The package should match your health goals rather than simply having the largest number of biomarkers.

MyDiagnostics can be considered when you want to measure relevant blood and organ-function markers rather than relying only on a biological-age calculator.

Speak with a qualified healthcare professional if you have persistent symptoms, significantly abnormal blood-test results, high blood pressure, diabetes, unexplained weight changes, breathing problems, or concerns about memory and cognition. A biological-age or organ-age result should not be used to diagnose disease or change medication without medical advice.