Biological Age: From Lifestyle to Blood Work
Two people can share a birthday and be a decade apart on the inside. This tool estimates that gap two ways — quickly from your habits, and more precisely from a nine-marker blood algorithm called PhenoAge.
Chronological age only counts your birthdays. Biological age tries to measure how fast your body is actually wearing — and the two can drift surprisingly far apart. The research gold standard for measuring it is an epigenetic clock, which reads chemical marks (DNA methylation) layered onto your genes over time.[1] Those require a specialised lab. The calculator above uses two practical proxies: a lifestyle estimate, and PhenoAge, an algorithm you can run from an ordinary blood panel.
Where PhenoAge comes from
In 2018, Morgan Levine and colleagues published PhenoAge in the journal Aging.[2] They started with 42 clinical markers measured in a large US population sample (NHANES III) and used statistical modelling to find the smallest set that best predicted the risk of dying. The winner was a combination of nine blood markers plus chronological age. The resulting "phenotypic age" outperformed chronological age at predicting all-cause mortality across nearly every subgroup studied.
The nine markers
PhenoAge reads nine routine markers, each a window onto a different aging system — metabolism, inflammation,[3] kidney and liver function, immune status and red-cell health.[4] Rather than rate them here, we keep the calculator neutral and explain each one in depth on a dedicated page: the PhenoAge blood markers, explained. It covers what every marker measures and what higher or lower values generally indicate, with references.
What "phenotypic age" actually means
Phenotypic age is the formal name for the number Step 2 produces. It is not a direct reading of your cells or your DNA. It is the chronological age at which the average person in a large reference population would carry the same ten-year mortality risk that your own blood panel implies. If your nine markers and your age put you at the risk level of a typical 48-year-old, your phenotypic age is 48 - whether your passport says 40 or 56.
That construction is why the number is read as a gap rather than an absolute. Phenotypic age minus chronological age is what researchers call age acceleration, and in the NHANES IV validation a positive gap predicted death and age-related disease across every subgroup tested - including people whose individual lab values all sat inside the normal reference range.[6]
The Levine PhenoAge equation, written out
There is no secret to this calculator. The algorithm is a published two-step equation: a weighted linear score from the nine markers plus your age, converted into a ten-year mortality probability, then mapped back onto an age scale.[2]
Two details decide whether a calculator built on this equation gives sensible answers. The first is that the coefficients only work in one specific set of units - the ones in the table below. Enter albumin in g/dL where the equation expects g/L, or glucose in mg/dL where it expects mmol/L, and the result is not slightly off, it is meaningless. This is the most common reason two online PhenoAge calculators disagree by years on the same blood panel. The calculator above converts whatever units you pick before it touches the formula.
The second is that CRP enters as a natural logarithm, so it cannot be zero. A reported value of 0 or "<0.1" is treated here as a floor of 0.01 mg/dL.
| Marker | Unit in the equation | Coefficient | Typical adult range |
|---|---|---|---|
| Albumin | g/L | -0.0336 | 35-50 |
| Creatinine | µmol/L | +0.0095 | 60-110 |
| Glucose, fasting | mmol/L | +0.1953 | 3.9-5.5 |
| CRP, as ln(CRP) | mg/dL | +0.0954 | 0.01-0.30 |
| Lymphocytes | percent of white cells | -0.0120 | 20-45 |
| MCV | fL | +0.0268 | 80-100 |
| RDW | percent | +0.3306 | 11.5-14.5 |
| Alkaline phosphatase | U/L | +0.00188 | 30-120 |
| White blood cells | 103/µL | +0.0554 | 4.0-11.0 |
| Chronological age | years | +0.0804 | - |
Reference ranges differ between laboratories; the column above is a common adult interval, not a target. As a sanity check, a 40-year-old with mid-range values for all nine markers (albumin 45 g/L, creatinine 79 µmol/L, glucose 5.1 mmol/L, CRP 0.15 mg/dL, lymphocytes 30 percent, MCV 90 fL, RDW 13.3 percent, ALP 68 U/L, white cells 6.2) comes out at a phenotypic age of about 36.
Converting your lab units
European and UK reports usually arrive in SI units, US reports usually do not. These are the conversions the calculator applies internally, so you can check its arithmetic against your own printout.
| Marker | To the equation's unit | Back the other way |
|---|---|---|
| Albumin | g/L = g/dL x 10 | g/dL = g/L / 10 |
| Creatinine | µmol/L = mg/dL x 88.4 | mg/dL = µmol/L / 88.4 |
| Glucose | mmol/L = mg/dL / 18 | mg/dL = mmol/L x 18 |
| CRP | mg/dL = mg/L / 10 | mg/L = mg/dL x 10 |
| White blood cells | 103/µL = cells/µL / 1000 | cells/µL = 103/µL x 1000 |
| Lymphocytes, MCV, RDW, ALP | reported the same way worldwide | - |
One caveat on lymphocytes: the equation needs the percentage of white cells, not the absolute count. If your report only gives an absolute lymphocyte count, divide it by your total white cell count and multiply by 100.
Is this the "Yale" biological age calculator?
PhenoAge is often searched for as the Yale biological age calculator, and the reason is Morgan Levine's lab. The 2018 paper that defined the nine-marker phenotypic age and validated it across the NHANES IV cohort lists her at the Department of Pathology, Yale School of Medicine.[6] The companion paper from the same year, which trained the DNA-methylation version of PhenoAge on that measure, was written while she was at UCLA.[2]
Both are Levine papers and neither is a product. There is no official Yale tool to sign up for - there is a published equation, and anyone can implement it. That is what this page does, unchanged, in your browser.
What this number cannot do
The model was fitted on US adults in the NHANES survey, with the original training sample drawn from blood collected in the late 1980s and early 1990s. Assay methods have been standardised since, and the weights were never refitted for other populations, so treat the absolute figure as approximate and the trend across your own repeat tests as the useful part.
It is also a mortality-risk model and nothing more. It cannot say why a marker sits where it does, it is not validated in pregnancy, in children, during acute illness or in people on dialysis, and because CRP is log-transformed a single inflamed week can move the result by years. Nothing on this page is a diagnosis or medical advice; it is an educational estimate provided as-is. Take unexpected values, and any decision based on them, to a doctor.
How to read your result
If your estimate is below your chronological age, your biology is running younger than your birthday. If it's above, the marker breakdown shows which values contribute most to the formula, so you know where to look. Because the model is built from routine labs, the levers are the familiar ones: metabolic health, inflammation, and the organ and blood markers that respond to sleep, exercise, body composition, alcohol and not smoking. The lifestyle changes with the best evidence for a longer, healthier life — building cardio fitness, keeping muscle, sleeping 7-8 hours, a Mediterranean-style diet, low alcohol and not smoking — are the same ones that tend to nudge these markers in the right direction over months.[5]
An important caveat about single blood draws
PhenoAge is powerful over populations, but any one blood test is a snapshot. A cold, a hard workout the day before, dehydration, a flare of an inflammatory condition or certain medications can move CRP, white cells or glucose enough to shift the result by years — temporarily. The number is most meaningful when your markers are measured while you're well and fasted, and most useful watched as a trend over repeated tests rather than a one-off verdict. Treat a surprising result as a prompt to recheck and to talk to your doctor, not as a diagnosis.
PhenoAge vs. the epigenetic gold standard
If you want the most direct measure of biological age, laboratory epigenetic clocks — Horvath's original clock, the newer DNAm PhenoAge, and pace-of-aging measures such as DunedinPACE — read your DNA methylation and are the research reference standard.[1] They cost more and need a dedicated test. The blood-based PhenoAge you can calculate above is the practical, no-extra-cost proxy: it uses labs you may already have, it's validated against mortality, and you can repeat it every time you get blood drawn. If you do not have bloods to hand, the other calculators on the site work from lifestyle inputs alone.
What is the Levine biological age calculator?
It is the calculator in Step 2 above. "Levine biological age calculator" is the everyday name for PhenoAge, the phenotypic-age algorithm published by Morgan Levine and colleagues in 2018. It takes nine markers from an ordinary blood panel plus your chronological age and returns the age at which the average person would carry your level of ten-year mortality risk. This page implements the published equation exactly, in your browser, and shows the arithmetic contribution of each marker.
What is phenotypic age?
Phenotypic age is a biological-age estimate built from clinical phenotype - routine blood markers - rather than from DNA. Concretely, it is the chronological age at which the mortality risk of a reference population matches the risk your own markers imply. The gap between phenotypic age and your real age is called age acceleration, and a positive gap predicted death and age-related disease in every NHANES subgroup tested, even among people whose individual lab values were all inside the normal range.
Is this a biological age calculator blood test?
Step 2 is. It needs nine values from a standard panel: albumin, creatinine, fasting glucose, CRP, lymphocyte percentage, MCV, RDW, alkaline phosphatase and white blood cell count. Any routine blood panel ordered by a doctor usually contains all nine, and a home finger-prick kit can cover them too. Step 1 needs no blood at all and works from lifestyle answers, so you can get an estimate before you have any labs.
Is this the biological age calculator Yale researchers published?
It implements their equation. The 2018 NHANES IV paper that defined and validated nine-marker phenotypic age lists Morgan Levine at the Department of Pathology, Yale School of Medicine; the companion paper on the DNA-methylation version came from her time at UCLA. There is no official Yale product - only a published formula that anyone can implement, which is what this page does.
Are my lab values uploaded or stored?
No. The whole calculation runs locally in your browser in JavaScript. Your lab values never leave your device and are never sent to a server. Only your email address is stored, and only if you choose to have your result emailed to you.
Which units do I need to enter?
Whichever your report uses. Each field has a unit selector, and the calculator converts to the units the published coefficients require before it applies the formula: albumin in g/L, creatinine in micromoles per litre, glucose in millimoles per litre, CRP in mg/dL as a natural logarithm, lymphocytes as a percentage, MCV in fL, RDW as a percentage, alkaline phosphatase in U/L and white cells in thousands per microlitre. Getting those units wrong is the main reason different online PhenoAge calculators disagree by years on the same panel.
Is PhenoAge the same as an epigenetic clock?
Not exactly. PhenoAge is a clinical-biomarker estimate from a standard blood panel. The research reference standard is a laboratory epigenetic clock such as Horvath's, the DNA-methylation version of PhenoAge, or the DunedinPACE pace-of-aging measure, all of which read DNA methylation and need a dedicated test. The blood-based version here is a validated, no-extra-cost proxy you can repeat every time you get blood drawn.
Can my phenotypic age go down again?
The markers the equation reads are the ones that respond to metabolic health, inflammation and body composition, so repeated panels can move in either direction over months. But a single draw is a snapshot: an infection, a hard training session the day before, dehydration or a medication change can shift CRP, white cells or glucose enough to move the result by years. Watch the trend over several tests taken while you are well and fasted, not one number.
Should I make health decisions based on this?
No. This is an educational estimate, not a diagnosis and not medical advice, and it is provided as-is without warranty. The model predicts risk across populations; it says nothing about why one of your markers sits where it does. Discuss any abnormal value, or any result that surprises you, with a qualified doctor.
References
- Horvath S. DNA methylation age of human tissues and cell types. Genome Biol. 2013;14(10):R115. PubMed · doi:10.1186/gb-2013-14-10-r115
- 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. PubMed · doi:10.18632/aging.101414
- Franceschi C, Campisi J. Chronic inflammation (inflammaging) and its potential contribution to age-associated diseases. J Gerontol A Biol Sci Med Sci. 2014;69 Suppl 1:S4-9. PubMed · doi:10.1093/gerona/glu057
- Patel KV, Ferrucci L, Ershler WB, et al. Red blood cell distribution width and the risk of death in middle-aged and older adults. Arch Intern Med. 2009;169(5):515-523. PubMed · doi:10.1001/archinternmed.2009.11
- Li Y, Pan A, Wang DD, et al. Impact of Healthy Lifestyle Factors on Life Expectancies in the US Population. Circulation. 2018;138(4):345-355. PubMed · doi:10.1161/CIRCULATIONAHA.117.032047
- 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;15(12):e1002718. PubMed · doi:10.1371/journal.pmed.1002718
Source: PubMed (U.S. National Library of Medicine). Algorithm: Levine et al., Aging 2018. Citations include article DOIs above.