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Biological Age Calculator
Your PhenoAge from 9 everyday blood-test results, the research formula from Levine and colleagues, with a breakdown of which markers add years and which take them away.
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An educational estimate from a research formula, not a diagnosis. Discuss your results with your doctor.
A biological age calculator estimates how old your body seems, not how many birthdays you have had. This one uses Phenotypic Age (PhenoAge), a published formula that turns 9 routine blood test results and your chronological age into a single age in years.
The calculator gives 3 main benefits: a biological age from validated research instead of a lifestyle quiz, a breakdown of the years each blood marker adds or removes, and full privacy, since nothing leaves your browser. People use it to read their annual blood work, to track health changes between check-ups and to see which result matters most. It has 5 parts: date fields, 9 biomarker inputs, an SI and US unit switch, the biological age vs chronological age result and the marker breakdown chart.
What is Biological Age?
Biological age is an estimate of how old your body is from the way it works, measured with blood markers, DNA methylation, telomere length or physical tests. Chronological age counts the years since your birth. Biological age asks a different question: which age group does your body match?
2 people born on the same day show the gap. Both are 45 years old by the calendar. Their blood results differ, so their PhenoAge differs by 17.6 years.
−8.9 years vs calendar age
- Albumin 44 g/L
- Fasting glucose 5.1 mmol/L (92 mg/dL)
- CRP 1.2 mg/L
- RDW 12.8%
+8.7 years vs calendar age
- Albumin 40 g/L
- Fasting glucose 6.2 mmol/L (112 mg/dL)
- CRP 4.5 mg/L
- RDW 14.4%
Biological age goes by 6 other names: physiological age, body age, health age, functional age, phenotypic age and, for the DNA tests, epigenetic age. A biological age calculator, body age calculator and health age calculator usually mean the same kind of tool, but the inputs differ a lot from one tool to the next.
How to Use the Biological Age Calculator
To use the biological age calculator, enter your date of birth and blood test date, pick SI or US units, type in your 9 blood results and press Calculate. The process takes 5 steps.
- Date of birth06/15/1981Enter your date of birth.
PhenoAge works for adults aged 20 and over.
- Blood test date10/30/2026Set the blood test date.
Use the date the blood was drawn, not the report date.
- SI unitsUS unitsPick the units on your report.
SI for the UK, Canada, Australia and Europe. US for the United States and India.
- Albumin g/L44Type in all 9 results.
Match each unit to your lab report. CRP has its own mg/L or mg/dL menu.
- PhenoAge 36.1Difference −8.9Read the result.
Your PhenoAge, calendar age, the difference and a bar for each marker.
Press Load example values to try the calculator with person A's results first. The calculator warns you when a value sits far outside the usual adult range, which often means a unit mix-up.
Which Blood Tests Are Needed to Calculate Biological Age?
3 blood tests are needed to calculate biological age: a comprehensive metabolic panel (CMP), a complete blood count (CBC) with differential and a high-sensitivity C-reactive protein (hs-CRP) test. Many annual check-ups include the first 2. Ask for hs-CRP if it is missing, and fast for at least 8 hours before the draw so the glucose result counts as fasting.
Comprehensive metabolic panel
- Albumin
- Creatinine
- Glucose (fasting)
- Alkaline phosphatase
UK: U&Es, liver function tests, fasting glucose
Complete blood count with differential
- Lymphocyte %
- Mean cell volume
- Red cell distribution width
- White blood cell count
UK: full blood count (FBC)
High-sensitivity C-reactive protein
- C-reactive protein
A standard CRP test often reports only "under 5 mg/L", which is too coarse for the formula
Which unit setting matches your lab report
| Country | Albumin | Creatinine | Glucose | Setting |
|---|---|---|---|---|
| United States | g/dL | mg/dL | mg/dL | US units |
| India | g/dL | mg/dL | mg/dL | US units |
| United Kingdom | g/L | µmol/L | mmol/L | SI units |
| Canada | g/L | µmol/L | mmol/L | SI units |
| Australia | g/L | µmol/L | mmol/L | SI units |
Lymphocyte %, MCV, RDW, ALP and white cells use the same units everywhere; a white cell count of 5.8 ×10⁹/L equals 5.8 ×10³/µL. Check each unit on your own report: some labs mix systems.
Nine Blood Biomarkers Used in the Biological Age Formula
The 9 blood biomarkers used in the biological age formula are albumin, creatinine, fasting glucose, C-reactive protein, lymphocyte %, mean cell volume, red cell distribution width, alkaline phosphatase and white blood cell count. Levine's team picked them from 42 candidate markers in the third National Health and Nutrition Examination Survey (NHANES III), using data from 9,926 adults with more than 20 years of mortality follow-up. 2 markers lower PhenoAge as they rise (albumin and lymphocyte %), and 7 raise it.
Albumin
↑ higher = youngerThe main blood protein, made by the liver. Low albumin follows illness, poor nutrition and inflammation.
Creatinine
↑ higher = olderA muscle waste product cleared by the kidneys. Higher levels point to lower kidney filtration.
Glucose (fasting)
↑ higher = olderBlood sugar after at least 8 hours without food. Raised fasting glucose marks insulin resistance and diabetes.
C-reactive protein (CRP)
↑ higher = olderA liver protein that rises with inflammation. The formula takes its natural log, so each doubling adds the same years.
Lymphocyte %
↑ higher = youngerThe share of white cells that are lymphocytes. The share drops with age and chronic stress on the immune system.
Mean cell volume (MCV)
↑ higher = olderThe average size of red blood cells. Large cells follow low vitamin B12 or folate, alcohol use and liver disease.
Red cell distribution width (RDW)
↑ higher = olderHow much red cell sizes vary. RDW carries the largest weight per unit in the formula.
Alkaline phosphatase (ALP)
↑ higher = olderAn enzyme from the liver, bile ducts and bone. It rises with bile duct and bone disorders.
White blood cells (WBC)
↑ higher = olderThe total count of infection-fighting cells. Counts rise with infection, smoking and long-term inflammation.
Years per step measured at age 45 from mid-range values, with the other 8 markers held still. Reference ranges differ between labs; the range printed on your report wins.
PhenoAge in 3 lines
xb = −19.907 − 0.0336·albumin + 0.0095·creatinine + 0.1953·glucose
+ 0.0954·ln(CRP) − 0.0120·lymphocyte% + 0.0268·MCV
+ 0.3306·RDW + 0.00188·ALP + 0.0554·WBC + 0.0804·age
M = 1 − exp(−1.51714 · exp(xb) / 0.0076927)
PhenoAge = 141.50225 + ln(−0.0055305 · ln(1 − M)) / 0.090165
units: albumin g/L · creatinine µmol/L · glucose mmol/L · CRP mg/dLM is the modelled 10-year mortality risk, and PhenoAge is the age at which an average NHANES adult carries the same risk. US units are converted first: albumin g/dL × 10, creatinine mg/dL × 88.4, glucose mg/dL ÷ 18.016 and CRP mg/L ÷ 10. The calculator uses the full-precision coefficients from the BioAge research toolkit. Some published versions print the final divisor as 0.09165, which shifts results by 1 to 2 years; the calculator follows the original 0.090165.
How to Interpret Your Biological Age Results
To interpret your biological age results, subtract your calendar age from your PhenoAge. A negative difference means your blood markers match a younger average adult, and a positive difference means they match an older one. Researchers call the positive gap biological age acceleration.
PhenoAge minus calendar age
AgeCountLab's reading guide, not clinical cut-offs. A gap within 2 years sits inside normal test-to-test change. Mid-range healthy values give a PhenoAge below calendar age: at 45, the reference values in the chart below give 37.4.
Your result has 4 parts. PhenoAge is your biological age in years. Calendar age is your chronological age on the blood test date, to 1 decimal. The difference is the gap between the 2. The breakdown chart shows which markers push the result up or down, longest bars first. Each extra calendar year adds 0.89 years to PhenoAge, so PhenoAge tracks your real age closely and the markers move it from there.
Which markers add years, and which take them away
Each bar shows how many years a marker adds to (right) or removes from (left) your PhenoAge, compared with a healthy mid-range value, with everything else kept as entered. It updates as you type in the calculator.
Showing person A's example values. Enter your own results in the calculator to see your breakdown.
Different Methods of Measuring Biological Age
There are 7 methods of measuring biological age, including blood biomarker formulas, DNA methylation clocks and telomere length. They measure different things, so one person gets different numbers from different methods.
| Method | What it measures | What you need | Examples |
|---|---|---|---|
| Blood biomarker formulas | Organ function, inflammation and metabolism from routine labs | A blood draw | PhenoAge (this calculator), Klemera–Doubal method (KDM), homeostatic dysregulation, InsideTracker InnerAge |
| Epigenetic clocks | DNA methylation at CpG sites | A blood or saliva kit | Horvath, Hannum, DNAm PhenoAge, GrimAge, DunedinPACE; TruAge, MyDNAge |
| Telomere length | The protective caps on chromosome ends | A blood sample | Research and commercial telomere tests |
| Organ-specific clocks | Plasma proteins linked to single organs | A blood sample, research only | Proteomic aging clocks for 11 organs |
| Physical function tests | Strength, flexibility, balance, reaction speed and body shape | A stopwatch, ruler and tape measure | Push-ups, sitting-rising, sit-and-reach, one-leg stance, reaction time, waist-to-height |
| Wearable estimates | VO2 max, resting heart rate, heart rate variability and sleep | A watch or ring | Garmin Fitness Age, Oura Cardiovascular Age, WHOOP Age; Fitbit and Apple Watch cardio fitness |
| Lifestyle questionnaires | Self-reported habits | Answers about BMI, activity, sleep, smoking and alcohol | Online biological age quizzes |
How biological age measurement developed
- 2006Klemera and Doubal publish the KDM method for blood-based biological age.
- 2013Horvath's 353-CpG multi-tissue clock and Hannum's 71-CpG blood clock.
- 2018Levine publishes PhenoAge and DNAm PhenoAge (513 CpGs); Liu validates PhenoAge in NHANES IV.
- 2019GrimAge, an epigenetic clock trained on mortality.
- 2021The BioAge toolkit makes KDM, PhenoAge and homeostatic dysregulation reproducible.
- 2022DunedinPACE measures the pace of aging per calendar year.
- 2023Plasma protein clocks estimate the age of 11 separate organs.
Physical function tests
- Push-ups: upper body strength and endurance
- Sitting-rising test: sit on the floor and stand up, scored 0 to 10
- Sit-and-reach: hamstring and lower back flexibility
- One-leg stance: balance for 10 seconds
- Reaction time: speed of response to a signal
- Waist-to-height ratio: keep the waist under half your height
What the research shows
- A 2022 study of 1,702 adults aged 51 to 75 in the British Journal of Sports Medicine linked failing the 10-second one-leg stance with an 84% higher risk of death over a median of 7 years
- The UK's National Institute for Health and Care Excellence (NICE) advises keeping waist-to-height ratio under 0.5
- Fitness scores track physical reserve capacity but give no age validated against mortality the way PhenoAge does
What Factors Are Associated with Biological Aging?
There are 8 factors associated with faster biological aging, including smoking, physical inactivity and poor sleep. These are associations from population studies of biological age measures; each factor moves 1 or more of the 9 blood markers.
Smoking
Raises white cell count and CRP, the 2 inflammatory aging markers in PhenoAge.
Physical inactivity
The World Health Organization (WHO) advises adults to get 150 to 300 minutes of moderate activity a week.
Short sleep
Adults need 7 or more hours a night; short sleep raises fasting glucose and inflammation.
Heavy alcohol use
Enlarges red blood cells, which raises MCV, and strains the liver.
Obesity
A body mass index (BMI) of 30 kg/m² or more goes with higher CRP and glucose.
High blood sugar
Fasting glucose carries 2.2 years per mmol/L (18 mg/dL) in the formula.
Chronic inflammation
Long-term raised CRP marks inflammaging, the low-grade inflammation of older age.
Chronic stress
Long-term stress shifts white cell patterns and lowers the lymphocyte share.
Common Mistakes When Calculating Biological Age
There are 6 common mistakes when calculating biological age, including mixing up CRP units, using a non-fasting glucose and testing during an illness. The years below are measured on person A (45 years old, PhenoAge 36.1).
Mixing up CRP units
✕ Entering 1.2 mg/L as 1.2 mg/dL: +2.4 years
✓ Match the CRP menu to the unit on your report
Using a non-fasting glucose
✕ 7.0 mmol/L (126 mg/dL) after breakfast: +4.1 years
✓ Fast for at least 8 hours before the draw
Entering the lymphocyte count
✕ 1.9 ×10³/µL instead of 32%: +4.0 years
✓ Use the lymphocyte percentage
Testing while ill
✕ CRP 20 mg/L and WBC 11 during a chest infection: +6.2 years
✓ Test at least 2 to 3 weeks after you recover
Switching units by country
✕ Indian mg/dL results typed into SI fields
✓ Pick US units for mg/dL reports
Comparing different labs
✕ Reading a 1-year change between 2 labs as real
✓ Use the same lab and the same time of day
Limitations of Biological Age Calculations
Biological age calculations have 6 main limitations: a single snapshot, a US training population, lab differences, sensitivity to short illnesses, no use under age 20 and no diagnostic value.
What PhenoAge does
- Combines 9 routine blood results into 1 age
- Ranks mortality and disease risk across groups
- Shows which markers push the result up
- Tracks change across repeat blood tests
- Uses published, peer-reviewed coefficients
What it does not do
- Diagnose any disease or replace a doctor
- Predict one person's lifespan
- Fit children, teenagers or pregnancy, when albumin falls and ALP rises
- Account for lab method differences
- Ignore a recent cold, injury or hard training session
PhenoAge was trained on adults in the United States. Studies in other countries use it, but the calibration comes from NHANES. Talk to your doctor about any result outside the range on your lab report.
Scientific Research and References
The biological age calculator rests on 9 peer-reviewed papers, from the first blood-based method in 2006 to the 2022 one-leg balance study.
- Levine ME, et al. (2018). An epigenetic biomarker of aging for lifespan and healthspan. Aging 10(4):573–591. Builds PhenoAge from 9 blood markers in NHANES III and DNAm PhenoAge from 513 CpGs.
- Liu Z, et al. (2018). A new aging measure captures morbidity and mortality risk across diverse subpopulations from NHANES IV. PLoS Medicine 15(12):e1002718. Validates phenotypic age in 11,432 adults aged 20 to 84.
- Kwon D, Belsky DW (2021). A toolkit for quantification of biological age from blood chemistry and organ function test data: BioAge. GeroScience. Source of the full-precision coefficients used here.
- Klemera P, Doubal S (2006). A new approach to the concept and computation of biological age. Mechanisms of Ageing and Development. The KDM method.
- Horvath S (2013). DNA methylation age of human tissues and cell types. Genome Biology. The 353-CpG multi-tissue epigenetic clock.
- Hannum G, et al. (2013). Genome-wide methylation profiles reveal quantitative views of human aging rates. Molecular Cell. The 71-CpG blood clock.
- Lu AT, et al. (2019). DNA methylation GrimAge strongly predicts lifespan and healthspan. Aging. The GrimAge clock.
- Belsky DW, et al. (2022). DunedinPACE, a DNA methylation biomarker of the pace of aging. eLife 11:e73420. Built from 19 indicators of organ-system integrity over 2 decades.
- Araújo CG, et al. (2022). Successful 10-second one-legged stance performance predicts survival in middle-aged and older individuals. British Journal of Sports Medicine 56:975–980. 1,702 adults, 84% higher risk of death for those who failed the test.
Frequently Asked Questions
Can I Calculate Biological Age Without a Blood Test?
No, you cannot calculate PhenoAge without a blood test, but quizzes and fitness tests give a rough, unvalidated estimate. PhenoAge needs 9 blood results plus your age. Lifestyle questionnaires use BMI, physical activity, sleep, smoking and alcohol, and fitness checks use push-ups, the sitting-rising test, sit-and-reach, the one-leg stance, reaction time and waist-to-height ratio. None of those scores was tested against mortality data the way PhenoAge was.
Which Blood Tests Are Required for PhenoAge?
PhenoAge requires 3 routine blood tests: a comprehensive metabolic panel (CMP), a complete blood count (CBC) with differential and a high-sensitivity C-reactive protein (hs-CRP) test. The CMP gives albumin, creatinine, fasting glucose and alkaline phosphatase. The CBC gives lymphocyte %, mean cell volume, red cell distribution width and the white blood cell count. In the UK, the same results come from U&Es, liver function tests, a full blood count, fasting glucose and CRP.
Is Biological Age the Same as Phenotypic Age?
No, biological age is the general idea, and phenotypic age (PhenoAge) is one way to measure it. Biological age covers every method that estimates how old the body seems, including epigenetic clocks, telomere length and fitness tests. Phenotypic age is the blood-test method Morgan Levine and colleagues published in 2018, and this calculator uses it.
Is Biological Age More Accurate Than Chronological Age?
Yes, biological age predicts health risk more accurately than chronological age alone, but chronological age stays the exact measure of time since birth. In a 2018 PLoS Medicine study by Liu and colleagues, phenotypic age was linked with death from all causes after adjusting for chronological age and sex, across 871 deaths over 12.6 years of follow-up in NHANES IV. Chronological age is exact to the day; biological age is an estimate with error.
Can My Biological Age Be Younger Than My Actual Age?
Yes, your biological age can be younger than your actual age. Healthy mid-range blood results give a PhenoAge below the calendar age. At age 45, example person A in this article has a PhenoAge of 36.1, 8.9 years younger, with an albumin of 44 g/L, a fasting glucose of 5.1 mmol/L and an RDW of 12.8%.
Can Biological Age Change Over Time?
Yes, biological age changes over time, since each of the 9 blood markers changes. Fasting glucose and CRP shift within weeks. Red blood cells live about 120 days, so MCV and RDW change over 3 to 4 months. A cold or an infection raises CRP and white cells for a few weeks and pushes PhenoAge up until they settle.
Can Lifestyle Changes Reverse Biological Aging?
Yes, lifestyle changes lower biological age scores, but no study shows that aging itself reverses. Lower fasting glucose, lower CRP and a lower white cell count all reduce PhenoAge, and exercise, weight loss and stopping smoking move those markers. A lower score means healthier markers, not a younger body in every sense.
Does Biological Age Predict How Long I Will Live?
No, biological age does not predict how long one person will live. PhenoAge ranks mortality risk across groups of people. A higher PhenoAge means a higher average risk among people like you, not a date or a life expectancy for you.
How Often Should I Check My Biological Age?
Check your biological age every 6 to 12 months, using the blood tests from your routine check-ups. Shorter gaps mostly show day-to-day noise in CRP and glucose. Use the same lab, fast for at least 8 hours and test when you are well, so 2 results compare fairly.
Is This Biological Age Calculator Free?
Yes, this biological age calculator is free. There is no sign-up, no newsletter and no upload: the calculation runs in your browser and your results never leave your device. You pay only for the blood tests, if your doctor or health service charges for them.
Find your biological age from your blood test
Enter 9 routine blood results and the biological age calculator shows your PhenoAge, your biological age vs chronological age and the markers behind it.
Calculate biological age