# What is my biological age?

Estimates your biological age (phenotypic age, PhenoAge) from nine routine blood test results and your age with the Levine 2018 formula, and how far it is from your age in years.

- Page: https://www.acalculator.org/health/biological-age-calculator
- JSON spec: https://www.acalculator.org/health/biological-age-calculator.json
- Version: 879de34c4c36

## Default answer

Example with the default inputs (Age (years) 45, Lab units US, Albumin (g/dL) 4.5, Creatinine (mg/dL) 0.9, Glucose (mg/dL) 90, C-reactive protein (mg/L) 1, Lymphocytes (%) 30, Mean cell volume (fL) 90, Red cell distribution width (%) 13, Alkaline phosphatase (U/L) 70, White blood cells (×1000/µL) 6): Your biological age (PhenoAge) is 37.4 years.

## Inputs

| Key | Label | Description |
| --- | --- | --- |
| age | Age (years) | Your age in years on the day of the blood test. |
| units | Lab units | US units (albumin g/dL, creatinine and glucose mg/dL) or SI units (g/L, µmol/L, mmol/L). |
| alb | Albumin (g/dL) | Serum albumin in g/dL. |
| cr | Creatinine (mg/dL) | Serum creatinine in mg/dL. |
| glu | Glucose (mg/dL) | Fasting serum glucose in mg/dL. |
| albSi | Albumin (g/L) | Serum albumin in g/L. |
| crSi | Creatinine (µmol/L) | Serum creatinine in µmol/L. |
| gluSi | Glucose (mmol/L) | Fasting serum glucose in mmol/L. |
| crp | C-reactive protein (mg/L) | C-reactive protein (CRP or hs-CRP) in mg/L. |
| lym | Lymphocytes (%) | Lymphocytes as a percent of white blood cells. |
| mcv | Mean cell volume (fL) | Mean corpuscular volume (MCV) in femtolitres. |
| rdw | Red cell distribution width (%) | RDW in percent. |
| alp | Alkaline phosphatase (U/L) | Alkaline phosphatase (ALP) in units per litre. |
| wbc | White blood cells (×1000/µL) | White blood cell count in thousands per microlitre. |

## Outputs

| Key | Label | Description |
| --- | --- | --- |
| phenoAge | Biological age (PhenoAge) | 141.50225 + ln(−0.00553 × ln(1 − M)) ÷ 0.090165. |
| gap | Difference from your age (years) | PhenoAge − age: negative means younger than your age. |
| mortality | 10-year mortality score | M, the model’s 10-year chance of death, in percent. |

## Method

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 × e^xb ÷ 0.0076927); PhenoAge = 141.50225 + ln(−0.00553 × ln(1 − M)) ÷ 0.090165.

## Assumptions

- Units in the formula: albumin g/L, creatinine µmol/L, glucose mmol/L, CRP mg/dL (the typed mg/L ÷ 10), lymphocytes %, MCV fL, RDW %, ALP U/L, WBC 1000 cells/µL.
- US units convert as albumin g/dL × 10, creatinine mg/dL × 88.4 (KDIGO), glucose mg/dL ÷ 18.016.
- The formula was trained on US adults (NHANES III) to predict 10-year mortality; it is a research estimate, not a diagnosis.

## Worked examples

1. age = 45, units = us, alb = 4.5, cr = 0.9, glu = 90, crp = 1, lym = 30, mcv = 90, rdw = 13, alp = 70, wbc = 6 gives phenoAge = 37.374585, gap = -7.625415, mortality = 1.50157%. Source: Levine ME and others, An epigenetic biomarker of aging for lifespan and healthspan, Aging 2018;10:573, Table 1 (phenotypic age weights), https://pmc.ncbi.nlm.nih.gov/articles/PMC5940111/; The full PhenoAge formula (intercept −19.907, 1.51714, 0.0076927, 141.50225, 0.00553, 0.090165) as printed in https://pmc.ncbi.nlm.nih.gov/articles/PMC12172999/ (retrieved 2026-10-05).
2. age = 60, units = si, albSi = 38, crSi = 110, gluSi = 6.1, crp = 5, lym = 22, mcv = 95, rdw = 15, alp = 95, wbc = 8 gives phenoAge = 72.295204, gap = 12.295204, mortality = 29.712566%. Source: Levine ME and others, An epigenetic biomarker of aging for lifespan and healthspan, Aging 2018;10:573, Table 1 (phenotypic age weights), https://pmc.ncbi.nlm.nih.gov/articles/PMC5940111/; The full PhenoAge formula (intercept −19.907, 1.51714, 0.0076927, 141.50225, 0.00553, 0.090165) as printed in https://pmc.ncbi.nlm.nih.gov/articles/PMC12172999/ (retrieved 2026-10-05).
3. age = 30, units = us, alb = 4.8, cr = 0.8, glu = 85, crp = 0.3, lym = 35, mcv = 88, rdw = 12, alp = 60, wbc = 5 gives phenoAge = 14.325278, gap = -15.674722. Source: Levine ME and others, An epigenetic biomarker of aging for lifespan and healthspan, Aging 2018;10:573, Table 1 (phenotypic age weights), https://pmc.ncbi.nlm.nih.gov/articles/PMC5940111/; The full PhenoAge formula (intercept −19.907, 1.51714, 0.0076927, 141.50225, 0.00553, 0.090165) as printed in https://pmc.ncbi.nlm.nih.gov/articles/PMC12172999/ (retrieved 2026-10-05).

## FAQ

### What is biological age?

Biological age is an estimate of how old your body seems from measurements, rather than from your birthday. Two people of 50 can have different biological ages if one has blood results more typical of an older person.

### What is PhenoAge?

Phenotypic age (PhenoAge) is a biological age built by Morgan Levine and colleagues in 2018 from nine blood markers and age. It was trained to predict the 10-year risk of death in US adults and is expressed as the age with that average risk.

### Which blood tests do I need?

Albumin, creatinine, glucose, C-reactive protein (CRP), lymphocyte percent, mean cell volume (MCV), red cell distribution width (RDW), alkaline phosphatase and white blood cell count. They come from a comprehensive metabolic panel, a complete blood count with differential, and a CRP test.

### What does a negative difference mean?

A negative difference means your PhenoAge is lower than your age: your results look like those of a younger average person. A positive difference means they look older. The number moves with each test, so one result is a snapshot.

### Can I lower my biological age?

PhenoAge moves with its markers. Inflammation (CRP), blood sugar and RDW weigh a lot, and they respond to exercise, weight, sleep, not smoking and treating illness. Talk with your doctor about any abnormal result rather than chasing the score.

### How accurate is a biological age calculator?

PhenoAge predicted death and disease better than age alone in the study population, but it is an average model. An infection or a short-term illness can raise CRP or white cells and add years for a while. Use it to follow trends, not to judge your health.

## Sources

- Levine ME, Lu AT, Quach A, and others. An epigenetic biomarker of aging for lifespan and healthspan. Aging (Albany NY). 2018;10(4):573-591, Table 1, retrieved 2026-10-05. https://pmc.ncbi.nlm.nih.gov/articles/PMC5940111/
- The full PhenoAge formula (intercept and constants) as printed in a 2025 open-access study, retrieved 2026-10-05. https://pmc.ncbi.nlm.nih.gov/articles/PMC12172999/
- KDIGO 2012 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease (1 mg/dL creatinine = 88.4 µmol/L). https://kdigo.org/guidelines/ckd-evaluation-and-management/
- Meidenbauer JJ, Mukherjee P, Seyfried TN. Nutrition & Metabolism. 2015;12:12 (glucose mg/dL ÷ 18.016 = mmol/L), retrieved 2026-10-05. https://pmc.ncbi.nlm.nih.gov/articles/PMC4367849/