Phenotypic Age Calculator: Biological Age from Blood Tests

Estimate your biological age from nine standard blood-panel markers, using the published Levine PhenoAge model.

  • 3 cited sources
  • Calculates in your browser

You’ll need a blood test for this one. All nine markers below have to come from your own results — albumin, creatinine, glucose, hs-CRP, lymphocyte %, MCV, RDW, alkaline phosphatase and white blood cells. Nothing is estimated or filled in for you, so there is no score until every one is entered.

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Appears here as you enter your details. No demo figures — the number is yours, or it is nothing.

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Methodology

Phenotypic Age (PhenoAge) is the clinical, blood-based biological-age measure developed by Levine and colleagues (Aging, 2018; originally derived in J Gerontol A, 2013). It combines nine routine blood markers with chronological age into a single estimate of biological age, built to predict differences in mortality risk between people of the same calendar age.

The calculation runs in three stages. First, a weighted linear combination of the markers:

xb = −19.90667 + Σ(coefficient × marker) + 0.08035356 × age

with the published coefficients (each marker in the exact unit its coefficient expects):

MarkerUnitCoefficient
Albuming/L−0.03359355
Creatinineµmol/L+0.009506491
Glucosemmol/L+0.1953192
ln(C-reactive protein)mg/dL+0.09536762
Lymphocytes%−0.01199984
Mean corpuscular volumefL+0.02676401
Red cell distribution width%+0.3306156
Alkaline phosphataseU/L+0.001868778
White blood cells10⁹/L+0.05542406
Ageyears+0.08035356

Second, that score is converted to a 10-year mortality estimate under a Gompertz proportional-hazards model. Third, the mortality estimate is back-transformed to the age at which the population-average person carries the same risk, your Phenotypic Age.

We took these coefficients directly from the authors' own published code (the BioAge R package) and locked our implementation to a reproduced worked example, cross-checked two independent ways, before shipping.

A note on CRP units. The formula uses the natural log of CRP in mg/dL. This calculator accepts CRP in mg/L (the common UK unit) or mg/dL and converts internally. A reported value of zero is floored to 0.01 mg/dL so the logarithm stays defined.

Interpreting your result

A Phenotypic Age lower than your chronological age is the favourable direction, at population level it is associated with lower mortality risk. But this is an association across large groups, not a forecast for you: two people with the same PhenoAge can have very different futures.

Treat the number as a conversation-starter with your doctor, not a verdict. It is also a snapshot, a recent infection, injury or flare of inflammation raises CRP and white cell count and will push the estimate up temporarily, then settle. If your result surprises you, the most useful next step is to discuss the underlying blood values with a clinician.

Limitations

  • PhenoAge reflects the day's blood panel, not a stable trait, acute illness and inflammation move it.
  • It was derived and validated primarily in US (NHANES) data; performance in other populations may differ.
  • Nine markers cannot capture everything about ageing; the model is a useful summary, not the whole picture.
  • This is a research measure of population risk, not a medical test or a diagnosis. Nothing here should be used to start, stop or change any treatment, that is a decision for you and your clinician.

Sources

Pull the receipts, 3 cited sources

FitTools · sources

  1. 01 Levine ME, et al. An epigenetic biomarker of aging for lifespan and healthspan. Aging 2018;10:573-591 (clinical Phenotypic Age)
  2. 02 Levine ME. Modeling the rate of senescence: can estimated biological age predict mortality? J Gerontol A 2013;68:667-674 (original derivation)
  3. 03 Kwon D, Belsky DW. BioAge R package, phenoage_calc.R (authors' reference implementation; source of the exact coefficients used here)

Every formula cited ✓

Frequently asked questions

What is phenotypic age?
Phenotypic Age (PhenoAge) is an estimate of biological age derived from nine routine blood markers plus your chronological age. It was built to track differences in ageing and mortality risk across people of the same calendar age, and a lower PhenoAge is associated, at population level, with better long-term outcomes.
Which blood tests do I need?
Albumin, creatinine, fasting glucose, C-reactive protein (CRP), lymphocyte percentage, mean corpuscular volume (MCV), red cell distribution width (RDW), alkaline phosphatase (ALP) and white blood cell count, all from a standard metabolic panel plus a full blood count and hs-CRP.
How accurate is PhenoAge?
It is a validated research measure of population-level mortality risk, not a personal prediction. Two people with the same PhenoAge can have very different futures. Treat a difference from your chronological age as a general signal to discuss with your doctor, not a verdict.
What is a good phenotypic age?
A PhenoAge lower than your chronological age is generally the favourable direction. But the number is only as good as your blood results on the day, and inflammation from a recent illness, for example, can raise CRP and WBC and push the estimate up temporarily.
Is my data private?
Yes. Every calculation runs entirely in your browser. Your blood values are never sent to us or anyone else, and nothing is stored.
Can I use this instead of seeing a doctor?
No. This is an educational estimate from a published formula, not a medical test. Any concern about your blood results or your health belongs with a qualified clinician.

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