Biological age: calculate your PhenoAge using a blood test
Turn nine blood markers and your chronological age into a PhenoAge estimate. French units are converted locally, and every step remains verifiable.
Short answer
PhenoAge estimates a biological age from your age and 9 common blood tests, including albumin, creatinine, blood glucose, CRP and a blood count. It was developed to predict mortality in a large US survey. It is a research indicator, not a diagnosis.
Calculator
Validated inputsResult calculated with BioAge
Your PhenoAge estimate
orig = TRUECRP, white blood cells, lymphocytes and albumin can fluctuate during an acute episode. Do not use this calculation as a baseline until you have recovered.
The model has mainly been validated in adults aged 20 to 84. Beyond that range, extrapolation uncertainty increases.
Check the values used by the formula
| Marker | Input | Calculated value |
|---|
The displayed difference is simply PhenoAge minus chronological age. This is not the PhenoAgeAccel used in studies, which is a residual calculated in a reference population. No result should replace medical interpretation of each test.
What the tool measures
An accessible blood-based age estimate, but not a diagnosis
PhenoAge combines nine blood markers and chronological age to produce an age expressed in years. The model was built from mortality risk observed in NHANES III, then validated in another US cohort.
Its value is practical: albumin, creatinine, glucose, CRP, lymphocytes, MCV, RDW-CV, alkaline phosphatase and white blood cells may appear on a French lab report. Its main risk lies in the units. Entering CRP in mg/L instead of the expected mg/dL is enough to distort the calculation.
This tool applies the coefficients from the orig = TRUE option in the scientific BioAge package. It performs conversions in your browser without sending or storing the values. The result summarizes a statistical profile. It does not measure the age of each organ or predict a date of death.
Interpreting the result
Interpret without overpromising
The main result is PhenoAge in years. The tool also displays a raw difference calculated as follows: PhenoAge − chronological age.
- A positive difference only means that the calculated score exceeds chronological age.
- A negative difference means that the calculated score is lower.
- Neither represents years of life lost or gained.
This raw difference is not the PhenoAgeAccel used in publications. PhenoAgeAccel is the residual from a regression of PhenoAge on age in a reference population. This distinction matters because the simple difference varies systematically with age.
Before looking at the overall score, compare each test result with your laboratory's reference ranges and your medical context. High blood glucose, persistently elevated CRP or a kidney abnormality should never be reduced to its effect on PhenoAge.
Calculation and assumptions
Methodology
The formula expects the following units: albumin in g/L, creatinine in µmol/L, glucose in mmol/L, CRP in mg/dL before the natural logarithm, lymphocytes as a percentage, MCV in fL, RDW-CV as a percentage, alkaline phosphatase in U/L and white blood cells in G/L.
The available conversions are transparent:
- Albumin: g/dL × 10 to obtain g/L.
- Creatinine: mg/L × 8.84 to obtain µmol/L.
- Glucose: g/L × 5.55 to obtain mmol/L.
- CRP: mg/L ÷ 10 to obtain mg/dL.
- Absolute lymphocytes: G/L ÷ white blood cells in G/L × 100 to obtain a percentage.
The calculation follows the BioAge code and uses 0.090165 in the final denominator. The correction to the 2019 article shows 0.09165. This page documents this discrepancy and retains the package version so that the result is reproducible with its reference implementation.
Sources consulted
Sources
- Liu, Z. et al. (2018) : A new aging measure captures morbidity and mortality risk across diverse subpopulations from NHANES IV
Validation study of Phenotypic Age in NHANES IV and statistical definition of PhenoAgeAccel.
- Liu, Z. et al. (2019): Correction to the Phenotypic Age equation
Correction adding the missing step in the equation published in 2018.
- Kwon, D. et Belsky, D.W. (2021) : A toolkit for quantification of biological age from blood chemistry and organ function test data
Publication describing the BioAge R package used to apply several biological age algorithms.
- BioAge: source code for phenoage_calc.R
Open implementation of the coefficients and constants used by this calculator.
Scope of validity
Limitations to know
- PhenoAge was developed and validated in US cohorts. There is no French clinical threshold that turns a given difference into a diagnosis.
- The score is sensitive to temporary states. Infection, acute inflammation, recent surgery or dehydration can alter several inputs.
- A value reported as "below" a detection limit is not an exact value. CRP must be strictly positive for its logarithm.
- The tool uses only the model's ten variables. It does not know your symptoms, medicines or laboratory-specific reference ranges.
- A change between two samples may come from biological or analytical variability. It does not prove that an intervention has slowed ageing.
Frequently asked questions
Before using the result
Can you use French blood test results?
Yes, if all nine markers are available. Select the exact unit from your lab report. The tool converts CRP to mg/dL, creatinine to µmol/L and glucose to mmol/L, among others.
Why can't CRP equal zero?
The formula uses the natural logarithm of CRP, which is undefined for zero. If the laboratory only reports a value below its detection limit, the exact result is unknown and the calculation becomes approximate.
Is the displayed difference my PhenoAgeAccel?
No. The tool displays PhenoAge minus chronological age. PhenoAgeAccel is a statistical residual calculated after regression on age in a reference population.
Are my lab results saved?
No. The calculation runs in your browser. This page does not transmit the values you enter or save them in local storage.