Understand the PhenoAge model
A biological age estimate from nine routine blood test results, using a published research formula.
By Peptide Clarity Guide · October 2026
Here's the short version
Type in your age and nine results from a routine blood test. PhenoAge, a formula published by Levine and colleagues in 2018, turns them into an estimated biological age. It's a research estimate, not a diagnosis, and it can't tell you whether a treatment works.
Your numbers
Use results from one blood draw. Most labs print all nine on a metabolic panel (CMP), a complete blood count (CBC) and a CRP test.
Your age on the day of the blood draw.
On a comprehensive metabolic panel (CMP).
On a metabolic panel (CMP).
On a metabolic panel. Use a fasting result if you have one.
Standard or high-sensitivity CRP. If it says less than a number, enter that number.
On a CBC with differential, sometimes shown as Lymphs %. Use the percent, not the count.
On a complete blood count (CBC).
On a CBC, sometimes listed as RDW-CV.
On a metabolic panel. Some reports say Alk Phos.
On a CBC. K/µL, 10³/µL and 10⁹/L are the same number.
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What PhenoAge measures
PhenoAge asks one question: at what age does an average US adult carry the 10-year mortality risk your blood results point to? The researchers built it from 9,926 adults in a national health survey, NHANES III, with more than 23 years of follow-up. Then they tested it on 6,209 different adults from a later round of the survey[1].
In that second group, PhenoAge tracked real age closely, with a correlation of 0.94. Each extra year of PhenoAge, compared with people the same age, came with about a 9% higher risk of death during follow-up[1]. A follow-up study of 11,432 adults found the same 9% link, including in people who reported no disease and had a normal weight[2].
So a number below your age means your markers look like those of a younger average adult in those surveys. A number above it means they look older. That's the whole claim.
The nine markers, and where to find them
All nine come from three common tests: a comprehensive metabolic panel (CMP), a complete blood count with differential (CBC) and a C-reactive protein (CRP) test. Use results from the same blood draw, and check the unit printed next to each one.
| Marker | Test | US report unit | Formula unit | Conversion |
|---|---|---|---|---|
| Albumin | CMP | g/dL | g/L | × 10 |
| Creatinine | CMP | mg/dL | µmol/L | × 88.4 |
| Glucose | CMP | mg/dL | mmol/L | × 0.0555 (about ÷ 18) |
| CRP | CRP or hs-CRP | mg/L | ln of mg/dL | ÷ 10, then the natural log |
| Lymphocytes | CBC with differential | % | % | None |
| MCV | CBC | fL | fL | None |
| RDW | CBC | % | % | None |
| ALP | CMP | U/L | U/L | None |
| WBC | CBC | K/µL | 1,000 cells/µL | None |
The formula, in full
Nothing here is our own model. The calculator runs the published equations from the paper's supplement, with the weights from its Table 1[1]. Each weight is multiplied by the marker in the paper's unit.
| Term | Weight | Unit |
|---|---|---|
| Albumin | −0.0336 | per g/L |
| Creatinine | 0.0095 | per µmol/L |
| Glucose | 0.1953 | per mmol/L |
| CRP (natural log) | 0.0954 | per ln(mg/dL) |
| Lymphocytes | −0.012 | per % |
| MCV | 0.0268 | per fL |
| RDW | 0.3306 | per % |
| ALP | 0.0019 | per U/L |
| WBC | 0.0554 | per 1,000 cells/µL |
| Age | 0.0804 | per year |
| Constant | −19.9067 |
Then three steps, exactly as the supplement prints them[1]:
- Add the constant and every marker times its weight. Call the total xb.
- Turn xb into a 10-year mortality risk:
M = 1 − exp(−exp(xb) × (exp(120 × 0.0076927) − 1) ÷ 0.0076927). - Turn that risk back into years:
PhenoAge = 141.50225 + ln(−0.00553 × ln(1 − M)) ÷ 0.090165.
Take the example the button above fills in: a 50-year-old with albumin 4.5 g/dL, creatinine 0.9 mg/dL, glucose 90 mg/dL, CRP 1.0 mg/L, lymphocytes 30%, MCV 90 fL, RDW 13%, ALP 70 U/L and white cells 6.0 K/µL. The terms add up to xb = −9.072. That's a 10-year risk of 2.24% and a PhenoAge of 41.9, in the model’s age-equivalent units. This does not mean the person is biologically eight years younger.
How to read your number
Treat it as one snapshot. CRP and white cells can climb for a while when you're fighting an infection, and glucose reads higher if you ate before the test. Either can push the estimate up for reasons that pass.
Two results a few months apart, from the same lab, tell you more than one. A change of a year or so between tests may be noise rather than a real shift. The formula was built on adults 20 and older, so it says nothing useful for teens.
What it can't tell you
- It isn't a diagnosis. A lab value outside its normal range matters on its own, whatever the estimate says. Ask a clinician about any result your report flags.
- It can't judge a treatment. The studies followed people over time. They didn't test whether lowering the number changes your health, and the follow-up study names the missing long-term data as its main limit[2].
- It isn't a DNA test. The same paper used this blood-based age to train a DNA methylation clock. This page runs the blood version[1].
- It doesn't know your history. Medicines, a recent illness, or a kidney or liver condition can move several markers at once.
Your numbers stay on this page
The math runs in your browser. Nothing you type is saved, sent to us or counted by analytics, and refreshing the page clears it. Our privacy page says the same.
Where to go next
If you're weighing a longevity program, start with your goal. Each shortlist names the providers that made the cut, with the one reason why.
Quick answers
- My CRP result says less than 0.3. What do I enter?
- Enter the cutoff, 0.3 in that case. Your real value is lower, so the estimate comes out a little older than it would with the exact figure.
- My lab reports g/L and µmol/L. Does that work?
- Yes. Switch the unit next to albumin, creatinine, glucose or CRP, and the calculator skips that conversion. The other five markers use the same units everywhere.
- Can a supplement or treatment lower my PhenoAge?
- This calculator can't tell you. PhenoAge was built to predict risk, and the studies behind it didn't test whether changing the number changes your health. Bring any plan to a clinician.
- Why does another PhenoAge calculator give a slightly different number?
- Small gaps usually come from rounding, the glucose conversion or a different alkaline phosphatase weight. This page uses the weights printed in the paper, including 0.0019 for ALP.
- Is this an epigenetic or DNA age test?
- No. The same paper used this blood-based age to train a DNA methylation test called DNAm PhenoAge. This page runs the blood version, on results you may already have.
Sources
- 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 29676998
- 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 30596641
This is general information, not medical advice. A licensed clinician can tell you what fits you. Health note