One tape measure, one division, and a number that tracks visceral fat — the kind BMI cannot see at all — better than almost anything else that needs no laboratory.
Enter waist and height in the same unit (both cm, or both inches) — the ratio is unaffected either way. Nothing you type here is sent anywhere, stored, or logged.
Waist-to-height ratio is your waist circumference divided by your height, in the same units. Measure waist circumference at the midpoint between the bottom of your lowest rib and the top of your hip bone, standing relaxed, after a normal exhale — not at the narrowest point of your torso, which most people instinctively reach for and which reads artificially low.
The Longevity Score calculator computes this automatically once you enter waist and height, so you never need to do the division by hand.
BMI cannot distinguish muscle from fat, and it says nothing about where fat is stored — a lean-but-visceral-fat body and a heavily muscled body can share an identical BMI while carrying very different risk. Waist-to-height ratio is a reasonable proxy specifically for visceral and abdominal fat, which is the metabolically active depot most strongly linked to insulin resistance and cardiovascular disease.
The public-health heuristic popularised by Ashwell and colleagues — "keep your waist circumference to less than half your height" — captures most of the value in one sentence, and this tool's thresholds sit close to that line, adjusted by sex.
For men, optimal is a ratio under 0.52, good is 0.52 to 0.57, and borderline is 0.57 to 0.62. For women the thresholds sit roughly 0.04 lower across the board — optimal under about 0.48 — reflecting typical differences in fat distribution and body composition between sexes.
A ratio above roughly 0.6 is associated with substantially elevated metabolic and cardiovascular risk in published cohorts, regardless of what the scale or a BMI calculation says.
Visceral fat responds to the same levers as most metabolic markers — a sustained calorie deficit, resistance training to preserve lean mass while losing fat, and reduced alcohol and refined-carbohydrate intake — and it tends to respond faster than subcutaneous fat to early changes in diet and activity.
See the structural dial for the other inputs and their limitations.
The sitting-rising test · Measuring three dials with no bloodwork · The structural dial
Calculate your Longevity Score free →Under 0.52 is optimal for men and under about 0.48 for women. A ratio above roughly 0.6 is associated with substantially elevated metabolic and cardiovascular risk in published cohorts, regardless of BMI.
Divide waist circumference by height, in the same units. Measure the waist at the midpoint between the bottom of the lowest rib and the top of the hip bone, standing relaxed after a normal exhale — not at the narrowest point of the torso.
Choose a question. Answers come from this site, and nothing you open is sent anywhere.
Under 0.52 is optimal for men and under about 0.48 for women. A ratio above roughly 0.6 is associated with substantially elevated metabolic and cardiovascular risk in published cohorts, regardless of BMI.
Divide waist circumference by height, in the same units. Measure the waist at the midpoint between the bottom of the lowest rib and the top of the hip bone, standing relaxed after a normal exhale — not at the narrowest point of the torso.
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.
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.