How to calculate your biological age (3 ways)
There are three ways to calculate biological age. (1) A lifestyle quiz estimates it from habits such as sleep, exercise, diet, stress, smoking and alcohol: free, instant, and approximate. (2) A blood-marker formula such as PhenoAge combines your age with nine routine blood test values. (3) A DNA-methylation (epigenetic clock) test reads chemical marks on DNA from a blood sample in a lab. Only the first needs no lab work. None of them is a medical diagnosis.
Way 1: lifestyle quiz (BioAge.io)
What it uses: your age plus answers about sleep, exercise, diet, stress, smoking and alcohol. How it works: it adds or subtracts years for each answer. The exact table is on the methodology page.
Worked example: a 50-year-old who sleeps 7.5 hours (−1 year), exercises five or more days a week (−3), eats a Mediterranean-style diet (−2.5), has low stress (−1.5), has never smoked (−1) and drinks within low-risk guidelines (0) gets 50 − 9 = 41.
Limits: it measures habits, not your body; the years are the site's own simplified weights. Try the free calculator.
Way 2: blood-marker formula (PhenoAge)
What it uses: your age and nine values from routine blood tests. The method comes from Levine et al., "An epigenetic biomarker of aging for lifespan and healthspan", Aging (Albany NY), 2018. The authors first built a clinical "Phenotypic Age" from nine biomarkers plus age, selecting them from 42 candidates in a US national health survey (NHANES III) and testing it in a later survey (NHANES IV) as a predictor of illness and death. They then built a DNA-methylation version ("DNAm PhenoAge") from it.
The nine values and their weights (Table 1 of the paper):
| Blood value | Unit the formula needs | Weight |
|---|---|---|
| Albumin | g/L | −0.0336 |
| Creatinine | µmol/L | 0.0095 |
| Glucose (serum) | mmol/L | 0.1953 |
| C-reactive protein (natural log of the value) | mg/dL | 0.0954 |
| Lymphocyte percent | % | −0.0120 |
| Mean cell volume | fL | 0.0268 |
| Red cell distribution width | % | 0.3306 |
| Alkaline phosphatase | U/L | 0.0019 |
| White blood cell count | 1000 cells/µL | 0.0554 |
| Age | years | 0.0804 |
| Constant | −19.9067 |
The calculation (from the paper's supplement):
- Add the constant to each weight × value; call the sum xb. (Use the natural logarithm of CRP.)
- Mortality score M = 1 − exp( − exp(xb) × (exp(120 × γ) − 1) / γ ), with γ = 0.0076927. (This is the modelled 10-year (120-month) risk of death.)
- Phenotypic age = 141.50225 + ln( −0.00553 × ln(1 − M) ) / 0.090165.
Worked example (invented values for a hypothetical 50-year-old; not a real person): albumin 45 g/L, creatinine 80 µmol/L, glucose 5.0 mmol/L, CRP 0.1 mg/dL, lymphocytes 30 %, MCV 90 fL, RDW 13.0 %, ALP 70 U/L, WBC 6.0, age 50.
| Term | Value × weight |
|---|---|
| Constant | −19.9067 |
| Albumin | −1.5120 |
| Creatinine | 0.7600 |
| Glucose | 0.9765 |
| ln(CRP) | −0.2197 |
| Lymphocytes | −0.3600 |
| MCV | 2.4120 |
| RDW | 4.2978 |
| ALP | 0.1330 |
| WBC | 0.3324 |
| Age | 4.0200 |
| xb (sum) | −9.0667 |
(exp(120 × 0.0076927) − 1) / 0.0076927 = 197.22, so M = 1 − exp(−exp(−9.0667) × 197.22) ≈ 0.0225 (2.25 %). Phenotypic age = 141.50225 + ln(−0.00553 × ln(1 − 0.0225)) / 0.090165 ≈ 41.9 years.
The result is an estimate from a statistical model, not a diagnosis. Limits: it needs a blood test with all nine values (most come from a standard blood panel plus an inflammation test such as CRP), and the model was built on US survey data. BioAge.io does not have a blood-test calculator yet.
Way 3: DNA-methylation (epigenetic clock) tests
What it uses: a blood sample analysed in a lab for chemical marks on DNA ("methylation"). Several "clocks" exist, and each turns the marks into an age. Examples named in research: DNAm PhenoAge (513 DNA sites, built to predict the clinical Phenotypic Age above; Levine 2018) and DNAmGrimAge, a "next-generation" clock described in the DAMA trial paper as better at predicting longevity and onset of age-related disease than earlier clocks (Fiorito 2021). Limits: different clocks measure different things and give different answers; a test result needs a lab and is not something you can calculate by hand.
The three ways side by side
| Lifestyle quiz | Blood-marker formula (PhenoAge) | DNA-methylation test | |
|---|---|---|---|
| Needs | Answers about habits | 9 blood values + age | Blood sample sent to a lab |
| Shows | An estimate of your habits | A modelled risk converted to "years" | A clock reading from DNA marks |
| Cost / time | Free, about a minute | Not covered on this page | Not covered on this page |
| Main limit | Not measured in your body | Needs recent lab values; built on US survey data | Different clocks disagree |
Frequently asked questions
How do I calculate my biological age at home?
The simplest way is a lifestyle quiz such as the free BioAge.io calculator. If you have recent blood test results, you can apply the PhenoAge formula shown above.
Which method is most accurate?
Blood and DNA-based methods measure biology directly, but different methods disagree with each other and none is a diagnosis. A lifestyle quiz is the least precise but the only one that needs no lab.
What blood tests do I need for PhenoAge?
Nine values: albumin, creatinine, glucose, C-reactive protein, lymphocyte percent, mean cell volume, red cell distribution width, alkaline phosphatase and white blood cell count, plus your age.
Is biological age the same as chronological age?
No. Chronological age is the years since birth; biological age is an estimate of how old your body behaves.
Can I lower my biological age?
Habits linked to a younger biological age in research include regular exercise and a better diet; see the methodology. A trial found a diet change slowed one epigenetic clock by about 0.66 years over two years.
Sources
- Levine ME et al. An epigenetic biomarker of aging for lifespan and healthspan. Aging (Albany NY), 2018. PMC5940111; supplement
- Fiorito G et al. The DAMA study. Aging Cell, 2021. PMC8520727
Educational information, not medical advice. A biological age estimate is not a diagnosis. Talk to a doctor about blood results. Not medically reviewed.