Guides

Written by Steve Fayzulayev. Clinically reviewed by Naomi Fayzulayev, FNP-C, MSN.

Last reviewed 2026-11-09. See our editorial policy and methodology.

Longer pieces that put the individual markers in context — what biological age is, what actually moves it, and how to get the measurements in the first place.

The biomarker and improvement pages answer specific questions. These guides answer the broader ones people usually ask first, and link down into the detail.

Fundamentals What is biological age? Chronological age counts birthdays. Biological age attempts to answer a harder question: how old does your body appear to be functioning right now? Read guide → Action How to lower your biological age A score can help you organize questions about your health, but it cannot tell you how long you will live or prescribe a plan. Start with the results you have and decide on next steps with your clinician. Read guide → Testing & Labs Measuring biological age without bloodwork A surprising amount of what predicts healthspan needs no laboratory. Blood work adds precision, but three dials are reachable with equipment most people already own. Read guide → Testing & Labs Discussing blood tests with your clinician There is no single longevity panel that is right for everyone. Start with existing results and discuss which, if any, additional tests make sense for your circumstances. Read guide → Testing & Labs Epigenetic age vs biological age "Biological age" is not one measurement. It is a category containing at least four quite different methods, which disagree with each other, cost wildly different amounts, and are useful for different purposes. Read guide → Testing & Labs Are biological age tests accurate? The honest answer is: accurate for some purposes and not others, and the purposes are easy to confuse. A test can be genuinely useful for tracking your own change while being close to meaningless as a statement about your absolute age. Read guide → Fundamentals What is heart age? Heart age calculators (the kind national heart foundations publish) are not measuring your heart directly. They are converting a calculated risk score into a more intuitive number — and that translation is worth understanding before you trust the output. Read guide → Testing & Labs Why a heart age calculator only tells part of the story A good heart age feels like clearance to stop worrying. It is not that — it is one system's risk score, converted into an age, while several other systems that independently predict how long you stay healthy and functioning were never asked about. Read guide → Fundamentals Five ways to measure biological age "Biological age" is not one test. At least five genuinely different methods exist, with different evidence behind each, and most calculators online use only one of them while implying they have covered the whole picture. Read guide → Action Longevity supplements: what the evidence supports Almost everything sold for longevity is supported by mouse data, mechanism, or a short trial measuring a surrogate marker. That is not the same as evidence that it extends healthspan in people, and the gap is where most of the money goes. Read guide → Life Stage What to prioritise, by decade Nothing on this page is age-specific biology. It is a sequencing argument: the same levers exist throughout, but their cost of delay differs sharply by decade, and some become much harder to pull later. Read guide → Life Stage Menopause and biological age Menopause is not a slow drift. Lipids, visceral fat, bone density, sleep and vascular function change together over a few years, which makes it one of the few periods where measuring before, during and after genuinely pays. Read guide → Fundamentals How much of ageing is genetic? "It runs in my family" is the most common reason people decide none of this is worth doing. The estimates do not support it — and the parts that genuinely are genetic are mostly identifiable, which changes what you do rather than whether you bother. Read guide → Fundamentals Healthspan vs lifespan: what's the difference? Global life expectancy has risen by roughly nine years since 1990. Healthy life expectancy — healthspan — has risen by only about seven. The difference between those two numbers is the part almost nobody tracks, and it is the part this entire tool exists to measure. Read guide → Action How to extend healthspan Healthspan describes the years spent in good health and function. No single score or habit guarantees it, but a manageable plan can support your health goals. Read guide →

Charts and reference

Lookup tables for the markers where the useful answer is a number rather than a paragraph.

VO₂ max by age and sexGrip strength by age and sexResting heart rate by age and sexHRV (RMSSD) by age and sexDHEA-S by age and sex Optimal vs standard ranges HOMA-IR calculator How fast each marker responds

Comparisons

Two terms people conflate, or two tools people have to choose between — what actually separates them.

Can ChatGPT interpret my lab results? Biological age vs chronological ageEpigenetic clock vs biomarker calculatorApoB vs LDL cholesterolHbA1c vs fasting glucoseVO₂ max vs resting heart rateHOMA-IR vs fasting insulinApoB vs non-HDL cholesterolCystatin C vs creatinine (eGFR)

Looking for something specific?

Biomarker pages explain what each number means and why the optimal range differs from your lab's. Improvement guides rank what actually moves each marker. The eight dials show how they combine.

Calculate your Longevity Score
Not medical advice. These are longevity-optimised reference ranges, which are deliberately stricter than standard clinical "normal" values. A value outside them does not mean you have a disease. Speak to a qualified healthcare professional before changing medication, supplements or training. Full disclaimer.
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What is biological age?

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.

How is the Longevity Score calculated?

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.

Do I need all 53 biomarkers?

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.

What can I measure without a blood test?

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.

Is this an anti-aging calculator? Is it a healthspan calculator?

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.

Why don't you have a quick quiz that skips biomarkers entirely?

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.

Why are your 'optimal' ranges stricter than my lab's normal range?

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.

Why not just upload my labs to ChatGPT?

For understanding a single result, do — a frontier chat model is genuinely good at that, often clearer than most medical sites, and it handles markers no fixed tool covers. The limitation is different from the one most people assume. A language model produces a plausible response rather than a computed one, so the same panel can score differently on different days. That is fine when exploring an idea and disqualifying when measuring change, because you cannot tell how much of a difference is you and how much is the method. Use both: a chat model to understand, a fixed instrument to track.

Is my health data private?

Biomarker values, assessment history and visit-preparation drafts are stored in your browser. The visit draft is separate from assessment exports and share links; copying or printing it can leave a copy outside the browser. There are no user accounts or third-party tracking. We keep anonymous usage totals on our own server, such as how many people reached a results screen on a given day; browsers sending Do Not Track or Global Privacy Control are not counted. Optional lab-report upload and AI coach features send data to Anthropic. Optional retest reminders send an email address, date and reminder label to our service and email provider. See our privacy policy for details.

Is this a medical diagnosis?

No. It is an educational and personal-tracking tool. The estimates are not clinically validated and must not replace evaluation by a qualified healthcare professional. If a result concerns you — particularly kidney markers, blood pressure or ApoB — take it to a doctor rather than acting on it alone.

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