Free Biological Age Calculator (PhenoAge)

Biological Age Calculator (PhenoAge)

Enter your age and nine routine blood values to get your Levine PhenoAge. It runs in your browser and sends nothing anywhere.

PhenoAge turns nine routine blood markers and your age into one number of years. The markers are albumin, creatinine, glucose, CRP, lymphocyte percent, MCV, RDW, alkaline phosphatase and white blood cell count. Morgan Levine's team built it from US survey data to predict mortality (Aging, 2018). It is a research measure, not a diagnosis.

Levine 2018 coefficients US and SI units Nothing leaves your browser

What your PhenoAge means

A PhenoAge above your age means your nine values resemble those of older adults in the survey data the model was built on. A PhenoAge below your age means they resemble those of younger adults. No guideline defines a healthy PhenoAge, so the number is a comparison with that data, not a pass or fail.

Morgan Levine and colleagues built the measure in two steps. They started with NHANES III, a nationally representative US survey with more than 23 years of mortality follow-up, and used 9,926 adults with complete blood data. A penalized Cox regression narrowed 42 candidate markers plus age down to nine markers plus age. A Gompertz model turned those into a 10-year mortality score, and the score was converted into years.

They then checked it in NHANES IV: 6,209 adults followed for up to 12 years. After adjusting for chronological age, each extra year of phenotypic age came with a 9% higher risk of all-cause mortality (hazard ratio 1.09). The hazard ratios were 1.10 for cardiovascular death and 1.20 for diabetes death, and the Alzheimer's estimate (1.04) was not statistically significant.

Input	Unit in the model	If the value is higher, PhenoAge is	Where to find it
Albumin	g/L	Lower	Comprehensive metabolic panel
Creatinine	µmol/L	Higher	Comprehensive metabolic panel
Glucose	mmol/L	Higher	Comprehensive metabolic panel
C-reactive protein (natural log)	mg/dL	Higher	Separate CRP or hs-CRP test
Lymphocyte percent	%	Lower	CBC with differential
Mean cell volume (MCV)	fL	Higher	Complete blood count
Red cell distribution width (RDW)	%	Higher	Complete blood count
Alkaline phosphatase	U/L	Higher	Comprehensive metabolic panel
White blood cell count	10³ cells/µL	Higher	Complete blood count
Chronological age	years	Higher	Your birth date

Eight of the nine markers sit on a CBC with differential and a CMP. Our guides explain both: how to read a CBC and how to read a CMP. The CRP is the missing piece for most people, and the CRP blood test guide covers when to ask for it.

What PhenoAge can't tell you

The paper tested whether PhenoAge predicts who dies sooner across large groups. It did not test whether lowering your own PhenoAge lowers your risk. An infection in the days before your blood draw raises CRP and white cell count, and both push the result up. Creatinine reflects muscle mass as well as kidney function, so muscle mass moves the result too.

Worked example: a 45-year-old

Albumin 4.5 g/dL, creatinine 0.90 mg/dL, glucose 90 mg/dL, CRP 1.0 mg/L, lymphocytes 30%, MCV 90 fL, RDW 13.0%, alkaline phosphatase 70 U/L, white cell count 6.0.

Step 1: convert to the model's units

albumin 4.5 g/dL × 10 = 45 g/L
creatinine 0.90 mg/dL × 88.42 = 79.6 µmol/L
glucose 90 mg/dL ÷ 18.0182 = 4.99 mmol/L
CRP 1.0 mg/L ÷ 10 = 0.1 mg/dL, ln(0.1) = −2.303

Step 2: the weighted sum (rounded to the digits the paper prints)

xb = −19.907 − 0.0336×albumin + 0.0095×creatinine + 0.1953×glucose
     + 0.0954×ln(CRP) − 0.0120×lymph% + 0.0268×MCV + 0.3306×RDW
     + 0.0019×ALP + 0.0554×WBC + 0.0804×age
   = −9.48

Step 3: mortality score, then years

M = 1 − exp(−1.51714 × exp(xb) ÷ 0.0076927) = 0.0150
PhenoAge = 141.50225 + ln(−0.00553 × ln(1 − M)) ÷ 0.090165 = 37.3

A 45-year-old with these values gets a PhenoAge of 37.3, which is 7.7 years below their age. The calculator above uses the unrounded coefficients from the reference implementation, so it can differ from a hand calculation with the rounded ones by under a tenth of a year.

CRP enters through its natural log, so the same ratio always moves the result by the same amount. In this example, taking CRP from 1.0 to 10 mg/L adds 2.4 years, and so does taking it from 0.5 to 5.

Getting a PhenoAge you can trust

Use values from one blood draw. A CBC with differential and a CMP are routine, and your last report may already hold eight of the nine. CRP is the one most people lack, because it is not part of a standard CBC or CMP. Ask for it by name at your next draw.

Test when you are well. Infection and injury raise CRP and white cell count, and both push PhenoAge up. A CRP above 10 mg/L usually points to infection or injury, so retest after you recover. Use a fasting glucose if you have one, since a draw after a meal runs higher.

Read the right line on your report. CBC reports print lymphocytes twice, as a percentage and as an absolute count, and the model wants the percentage. If you only have the count, switch the unit above and the calculator divides it by your white cell count. RDW also prints twice: RDW-CV is a percentage and RDW-SD is in fL. The model uses the percentage.

Watch for a "less than" CRP. A standard CRP often prints as below a detection limit. The calculator accepts that and labels the result an upper estimate. The limit can cost you real years: a true CRP of 0.5 mg/L reported as "<5" adds about 2.4 years to the result.

This calculator uses the blood-chemistry measure from the paper, called phenotypic age. The same paper also trained a DNA-methylation clock, DNAm PhenoAge, which needs a different test. For what a recent study found moves those clocks, see our commentary on epigenetic aging clocks. For the blood markers longevity researchers track and who cites each target, see the longevity section.

Frequently asked questions

How can I calculate my biological age?

Enter your age and nine blood values into the calculator on this page: albumin, creatinine, glucose, C-reactive protein, lymphocyte percent, MCV, RDW, alkaline phosphatase and white blood cell count. It applies the Levine PhenoAge formula (Aging, 2018) and returns a biological age in years. All nine values come from a CBC with differential, a comprehensive metabolic panel and a CRP test, so most people already have eight of them on a routine report.

What is the most accurate biological age test?

No test has a proven claim to that title. Biological age cannot be measured directly, so researchers judge a clock by how well it predicts death and disease across large groups. In Levine's 2018 paper, each extra year of the blood-chemistry measure used here (phenotypic age) came with a 9% higher risk of all-cause mortality in NHANES IV after adjusting for chronological age (HR 1.09). The authors reported that their DNA-methylation version, DNAm PhenoAge, outperformed earlier clocks for mortality, cancers, healthspan, physical functioning and Alzheimer's disease. Both results describe groups of people, not how close a clock lands for one person.

How can I get my biological age checked?

Ask your doctor for a complete blood count with differential, a comprehensive metabolic panel and a CRP test. Together they cover all nine inputs. CRP is not part of a standard CBC or CMP, so you may need to request it by name. Enter the results into the calculator or upload the report to FixFirst. DNA-methylation clocks are a different kind of test, and this calculator does not need one.

Is there a free online biological age test available?

Yes. This calculator is free, needs no account and runs in your browser, so your values are never sent anywhere. It uses blood values and the published PhenoAge formula, unlike quizzes that estimate biological age from lifestyle answers. You need a recent blood report to use it.

Do I need hs-CRP, or does a standard CRP work?

Standard CRP and high-sensitivity CRP (hs-CRP) measure the same protein, and hs-CRP resolves lower values. The paper lists CRP in mg/dL and does not name the assay in its main text. The BioAge reference implementation combines both assays after converting units. Enter whichever you have, in the unit your report prints. If the report says below a detection limit, such as <0.3 or <5, type that number and treat the result as an upper estimate. The limit matters: a true CRP of 0.5 mg/L reported as <5 adds about 2.4 years.

Is this the same as DNAm PhenoAge?

No. The Levine paper built the blood-chemistry measure first (phenotypic age, which this calculator computes), then trained a DNA-methylation clock on 513 CpG sites to estimate it. People often call both PhenoAge. This calculator needs no DNA test.

Is a PhenoAge below my age good?

It means your nine values resemble those of a younger person in the survey data the model was built on. The paper showed that PhenoAge predicts mortality across groups (HR 1.09 per year, adjusted for age). It did not test whether changing your own PhenoAge changes your outcome. One draw is one data point, so retest when you are well before reading much into it.

Note: This calculator is for information and does not replace medical advice. PhenoAge is a research measure with no clinical cut-offs and is not used to diagnose or treat any condition.