One of these numbers is on your driver's licence. The other is an estimate of how your body is actually holding up — and the gap between them is the entire reason this calculator exists.
| Biological age | chronological age | |
|---|---|---|
| What it measures | Function of your vascular, metabolic, cognitive and other systems | Time since birth |
| Can it change direction? | Yes — can run younger or older than chronological age, and can improve | No — only increases |
| How it's measured | Biomarkers, physical tests, or DNA methylation (epigenetic clocks) | A calendar |
| Is there one number? | No — depends on the method; different clocks/panels can disagree | Yes, universally agreed |
| What predicts health outcomes better? | More strongly, in multiple independent cohort studies | Weakly, on its own |
Chronological age is simply how long you have been alive, counted the same way for everyone. It is not a measurement of health — it is a measurement of time, and time passes at the same rate for everyone. Two 50-year-olds can have dramatically different cardiovascular fitness, insulin sensitivity and cognitive performance, and chronological age cannot express any of that difference.
Biological age is an attempt to answer a different, harder question: given everything measurable about this body right now, how old does it appear to be functioning? It is not one universally defined number — it is an estimate, and different methods (biomarker panels like this one, physical performance tests, or epigenetic clocks that read chemical marks on DNA) can produce different estimates for the same person, because they are measuring different things.
Genetics, sleep, training, diet, stress and chronic disease all leave measurable marks on the body at different rates in different people, which is exactly why biological age can run younger or older than the calendar. A 45-year-old competitive cyclist with excellent lipids and low inflammation can plausibly score as biologically younger than their chronological age. A 45-year-old with untreated hypertension, poor sleep and high visceral fat can plausibly score older.
This divergence is not a rounding error or noise — it is the entire signal. Epigenetic-clock research (PhenoAge, GrimAge and related DNA-methylation-based measures) has repeatedly found that people whose biological age runs ahead of their chronological age — called age acceleration — carry measurably higher mortality and disease risk than age-matched peers, even after adjusting for conventional risk factors like smoking and existing disease. Chronological age alone does not capture that risk; the acceleration does.
Chronological age is not actionable — nothing you do changes how long you have been alive. Biological age is actionable by construction: every dial on this site is built from biomarkers that respond, on different timescales, to real changes in sleep, training, nutrition and treatment. That is the practical reason to care about the distinction at all — one number is a fact to accept, the other is a target you can move.
It is also why this calculator reports a biological age alongside the composite Longevity Score rather than either alone: the composite says how you are doing overall, and the biological-age framing keeps the number anchored to something concrete and comparable to the one piece of information everybody already has — how old they actually are.
Yes. It can also be higher. Unlike chronological age, which only ever increases, biological age reflects your current measurable state and can move in either direction as that state changes.
The underlying concept — that measurable biomarkers and DNA methylation patterns predict health outcomes independently of calendar age — is supported by a substantial and still-growing body of peer-reviewed research, particularly on epigenetic age acceleration and mortality. The specific number any calculator reports, including this one, is an estimate from a defined method, not a lab-certified diagnosis.
No single number guarantees an individual outcome. The research support is at the population level: people with more favourable biological age measures tend to have lower risk of disease and death on average. It is a risk indicator to act on, not a prediction for one person.
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Yes. It can also be higher. Unlike chronological age, which only ever increases, biological age reflects your current measurable state and can move in either direction as that state changes.
The underlying concept — that measurable biomarkers and DNA methylation patterns predict health outcomes independently of calendar age — is supported by a substantial and still-growing body of peer-reviewed research, particularly on epigenetic age acceleration and mortality. The specific number any calculator reports, including this one, is an estimate from a defined method, not a lab-certified diagnosis.
No single number guarantees an individual outcome. The research support is at the population level: people with more favourable biological age measures tend to have lower risk of disease and death on average. It is a risk indicator to act on, not a prediction for one person.
Chronological age counts birthdays. Biological age estimates how old your body appears to be functioning, based on measurable biomarkers. Two people born the same year can differ by a decade or more in vascular stiffness, insulin signalling or cardiorespiratory fitness. Biological age makes that gap explicit — and unlike your birthday, it can move in either direction.
Each biomarker you enter is scored against longevity-optimised reference ranges and grouped into one of eight dials. Every dial produces its own biological age, and those are combined using fixed weights into a single composite, then expressed as a Longevity Score from 0 to 100. The weighting reflects how strongly each system predicts healthspan: structural and vascular carry the most, hormonal the least.
No. The short form contains a subset of scoring inputs plus context-only fields, and you can leave any of them blank. It is not a recommendation to obtain tests. Missing values are excluded from the calculation — never treated as zero or as 'normal'. A dial with no scored data is dropped entirely and the remaining weights renormalise.
Some inputs can be measured without bloodwork. Blood pressure needs a home cuff and waist-to-height needs a tape measure. Wearable estimates vary; the floor-based sitting-rising test carries a fall risk and should only be attempted if safe.
Both terms describe what this tool does, and which one fits depends on what you are asking. "Anti-aging" is the term most people search, and loosely means anything aimed at slowing or reversing age-related decline — this tool fits that description if you score your dials and act on what you find. "Healthspan calculator" is the more precise term: healthspan is the number of years lived without serious chronic disease or disability, and that cannot be measured directly, so this tool scores eight systems that each function as an early-warning proxy for it. Either way, the method is the same: real biomarkers, published thresholds, no vanity-metric framing.
Several popular tools ask only about habits — exercise days, sleep hours, smoking, diet quality — and return a single precise-looking age. We looked at the research behind that approach and chose not to build it. Published studies do show real, individually-measured links between specific habits and epigenetic age acceleration, but those effect sizes come from different study populations, different DNA-methylation clocks and different measurement units. Adding them together into one number is not something the underlying research actually supports — it produces a precise-looking result built on an imprecise method. Our dials use direct physiological measurements instead: a real blood pressure reading, a real VO₂ max, a real ApoB value. Several dials score from home-measurable data alone with no quiz-guessing involved — see what you can measure without a blood test, above.
Standard reference ranges describe what is common in a general population, which now includes a great deal of metabolic dysfunction. They are tuned to flag disease, not to identify what is optimal for a long healthspan. A fasting insulin of 20 µIU/mL sits inside most labs' normal range and is strongly associated with insulin resistance. This tool uses longevity-optimised thresholds instead, so a flag here means room for optimisation — not a diagnosis.