Biological Age Calculator
You have two ages. One is printed on your birth certificate and moves forward whether you like it or not. The other is your biological age: how old your cells, organs, and systems actually behave, and it can run years ahead of or behind the calendar.
That second number is the one worth knowing. Studies of biological age find it predicts disease risk and lifespan more sharply than the years you have been alive, because it reflects the present state of your metabolism, your inflammation, and your organ function rather than just the date on your ID. Two people born the same week can sit a decade apart biologically.
It is also the only one of the two you can change. The habits you keep and the markers in your blood both move it, in either direction, which makes a high number a signal rather than a verdict. The calculator below estimates your biological age two ways: a fast lifestyle read that needs nothing but a minute, and a clinical-grade calculation built from a standard blood panel.
How this calculator works
There are two ways to answer the question of how old your body really is, and this tool offers both. They serve different purposes, and the difference between them is the entire point.
The quick estimate asks seven questions about how you live. It needs no bloodwork and takes under a minute, so anyone can use it. The trade-off is that it reads your habits, not your biology. The lab-based calculation uses the Levine PhenoAge algorithm, a peer-reviewed model that reads nine markers from a standard blood panel. It is far more accurate because it measures what is happening inside you rather than inferring it from behavior.
Method 1: The quick estimate
The quick estimate is a transparent additive model. It starts from your chronological age and adds or subtracts years based on factors with well-established links to how fast people age and how long they live. Each answer carries a fixed adjustment in years. Positive numbers push your estimated age up, meaning you are aging faster than the calendar. Negative numbers pull it down.
The factors it weighs are smoking status, physical activity, sleep, body composition, diet quality, and day-to-day stress. The tool sums these adjustments, caps the total to a sensible band so no single profile produces an absurd result, and never returns an age below 18. The result panel shows exactly which factors moved your number and by how much.
Be clear about what this is. It is a directional reflection of your habits, not a measurement of your physiology. Two people can give identical answers and have very different inflammation, blood sugar control, and organ function. For the number that can see those things, use the lab calculation.
Method 2: The lab-based PhenoAge
This is the rigorous one. PhenoAge was developed by Morgan Levine and colleagues and published in 2018. It was built on a large US population dataset, NHANES, and validated against real outcomes: it predicts mortality and age-related disease risk, and it distinguishes between two people of the same chronological age who are aging at different rates. It uses nine routine blood markers plus your age.
The nine markers are albumin (liver and nutritional status), creatinine (kidney function), glucose (metabolic health), hs-CRP (inflammation), lymphocyte percent (immune function), mean cell volume, red cell distribution width, alkaline phosphatase (liver and bone), and white blood cell count. The calculation combines them into a single weighted score, converts that score into a ten-year mortality risk, and maps that risk back onto the age scale to answer what age this risk profile corresponds to in the general population.
One technical detail matters here. The PhenoAge model was built on CRP measured in milligrams per deciliter, but US labs report hs-CRP in milligrams per liter, a number ten times larger. Many public calculators feed the raw value straight in without converting it, which inflates the score and reports people as older than they are. This calculator converts the units correctly, so you enter the value exactly as your lab reports it.
How to read your result
The headline number is your biological age. The number that matters most is the gap between it and your chronological age.
If your biological age is lower than your real age, your body is running ahead of the calendar, which is associated with lower disease and mortality risk. If it is higher, your biology is aging faster than your years, which is a signal worth taking seriously and, importantly, often reversible. A gap within about a year in either direction means you are tracking with your age. The further the gap opens, the stronger the signal.
One reading is a single data point. It tells you where you stand today. It does not tell you which direction you are heading, and direction is what you can actually change.
What can move the number around
The lab calculation is only as good as the values you feed it. Glucose should ideally be a fasting value, since a reading taken after a meal runs higher and inflates the result. Acute illness, a recent infection, or an injury can spike CRP and white blood cell count, temporarily making you look older, so avoid testing while sick. Dehydration, a very intense recent workout, pregnancy, and certain medications can all shift individual markers. Labs also differ slightly in their methods and reference ranges, so small run-to-run variation is normal.
This is why a single snapshot is a weaker tool than a trend. Markers tracked over time, under similar conditions, tell a far more reliable story than any one test.
Frequently asked questions
What is the difference between biological and chronological age?
Chronological age is how long you have been alive. Biological age estimates how old your body behaves at the cellular and organ level. Two people born on the same day can have biological ages a decade apart, because lifestyle and underlying health shift how fast the body ages.
How accurate is the quick estimate?
It is directional, not diagnostic. It captures behaviors with strong links to aging, but it cannot see what is happening inside your body. Treat it as a gut check and use the lab-based calculation for an actual measurement.
What blood tests do I need for the PhenoAge calculation?
A standard complete blood count and a metabolic panel cover almost all of it, plus a high-sensitivity CRP test, which is often ordered separately.
Can I lower my biological age?
Yes, and that is the point. Unlike chronological age, biological age responds to sleep, training, body composition, blood sugar control, and inflammation. Improving the markers behind the score moves the number, which is why tracking it over time is more useful than a single reading.
Is my data saved?
No. The entire calculation runs in your browser. Nothing you enter is stored or sent anywhere.
References
Levine ME, Lu AT, Quach A, et al. An epigenetic biomarker of aging for lifespan and healthspan. Aging (Albany NY). 2018.
Liu Z, Kuo P-L, Horvath S, Crimmins E, Ferrucci L, Levine M. A new aging measure captures morbidity and mortality risk across diverse subpopulations from NHANES IV. PLoS Medicine. 2019.
This page is for education, not medical diagnosis. Always interpret biomarkers with a qualified clinician.
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