How to Calculate Your Biological Age from a Blood Test for Free
PhenoAge estimates biological age from a panel that includes all nine PhenoAge markers. Here is the free HealthOS calculator and how to read the result.
You can calculate a free biological age estimate called PhenoAge from a panel that includes all nine PhenoAge markers. It uses your calendar age plus nine routine markers: albumin, creatinine, glucose, C-reactive protein, lymphocyte percentage, MCV, RDW, alkaline phosphatase and white blood cell count. C-reactive protein is the marker most often missing from routine check-ups. HealthOS has a free PhenoAge calculator that fills itself if you upload your lab PDF or photo at https://healthosx.com/blood first. The calculator is free, requires no account, and runs in the browser.
How can I calculate my biological age from a blood test for free?
Pull your last complete blood count (CBC), comprehensive metabolic panel (CMP) and a CRP or hs-CRP result. The nine values sit across those three tests. A PDF or photo up to 15MB works for the upload. Uploaded reports are sent to Anthropic’s Claude AI, or if unavailable to Google’s Gemini or OpenAI, to read the numbers, then discarded unless the optional keep-a-copy box is ticked. Earlier reports stay in the reader’s own browser, a second upload at https://healthosx.com/blood shows how each marker moved, and one tap can carry the numbers into the HealthOS app.
You can do this two ways:
- Upload the lab PDF or photo at https://healthosx.com/blood. Open the PhenoAge calculator at https://healthosx.com/blood/phenoage in the same browser. The report reader pulls the nine numbers and fills the calculator.
- Type your age and the nine values yourself. Nothing you type is sent anywhere.
Do not guess a missing value. If one marker is absent, the result cannot be calculated honestly.
The nine markers, and where to find them
On the CBC, look for lymphocyte percent, MCV, RDW and white blood cell count. On the CMP, look for albumin, creatinine, glucose and alkaline phosphatase. The last marker is C-reactive protein, from a standard CRP or high-sensitivity hs-CRP test. It is the one most often missing from routine check-ups.
| Marker | Panel | What the report calls it |
|---|---|---|
| Albumin | CMP | Albumin |
| Creatinine | CMP | Creatinine |
| Glucose | CMP | Glucose |
| Alkaline phosphatase | CMP | ALP |
| Lymphocytes | CBC | Lymphocyte % |
| MCV | CBC | Mean cell volume |
| RDW | CBC | RDW-CV |
| White blood cells | CBC | WBC count |
| C-reactive protein | CRP or hs-CRP | CRP or hs-CRP |
Scroll the table sideways for the rest →
All nine must be present. Do not guess a missing value.
If the report says CRP is below the detection limit, such as <0.3, enter 0.3. The units must match the field you are filling.
Why these nine markers predict age
PhenoAge comes from a 2018 study by Morgan Levine and colleagues (Levine et al., Aging, 2018;10:573-591). The team used data from about 10,000 US adults in the NHANES III survey and looked for the routine blood markers that, with calendar age, best predicted later mortality. The model combines those markers into a mortality risk score and then converts the score to an age. That age is your phenotypic age: the age at which an average person in the reference data had the same risk.
The nine markers are not arbitrary. Albumin and alkaline phosphatase reflect liver and general metabolism. Creatinine reflects kidney filtration. Glucose reflects metabolic control. C-reactive protein reflects systemic inflammation. White blood cells and lymphocyte percent reflect immune state. MCV and RDW reflect red blood cell health. The model combines markers across systems and, in the original study, predicted mortality better than calendar age alone.
PhenoAge below your calendar age means your blood markers look like those of a younger average person. It does not prove you are aging slowly.
What a PhenoAge result can and cannot tell you
In the original study, phenotypic age predicted mortality better than calendar age alone. But an individual blood draw is noisy. A single draw can move with infection, hard workout, dehydration or a bad night. If you have questions about timing or an abnormal result, discuss them with a clinician.
PhenoAge is an estimate for adults, not a diagnosis. A single PhenoAge number cannot diagnose a disease, cannot tell you how long you will live and does not replace a doctor's reading of an out-of-range lab value. It was built on adults, so it is not a pediatric tool. It is not a DNA methylation clock. A number inside the normal range still does not rule out a problem. If any marker is outside the lab range or you feel unwell, talk to a doctor sooner rather than relying on PhenoAge.
Does one normal blood test really show biological age?
Usually yes, if the panel has all nine markers. The common gap is CRP. Many annual check-ups run a CBC and CMP but skip CRP unless you ask. If your report has no CRP, the PhenoAge formula cannot be completed honestly. Wait for the next draw and ask your clinician whether adding hs-CRP is appropriate.
Upload your PDF or photo at https://healthosx.com/blood and open the free PhenoAge calculator at https://healthosx.com/blood/phenoage. The nine markers fill in if the report is read in the same browser, or you can type them yourself. The calculator is free, requires no account, and runs in the browser. A single number is a starting point, not a verdict.
Written by
HealthOS Research