Most of what is sold for this does nothing. The interventions that work are unglamorous — sleep, body composition, training, alcohol — and they work by removing the things suppressing production rather than by stimulating it.
Target600–900 ng/dL
The longevity-optimised range used by the hormonal dial. See what testosterone measures for the reasoning.
What to expect, and when
Sleep correction can show up within two weeks. Body composition change takes three to six months. Levels vary substantially within a single day and between days, so judge by two morning draws several weeks apart, not by one.
What works, in order of leverage
1. Sleep seven to nine hours
Most testosterone release happens during sleep. Restricting healthy young men to five hours a night lowers daytime levels by 10–15% within a week. This is the most underrated lever by a wide margin.
2. Get screened for sleep apnoea if you snore
A common, reversible and frequently missed cause of low testosterone. No amount of training compensates for an obstructed airway.
3. Reduce visceral fat
Adipose tissue converts testosterone to oestradiol via aromatase, so fat loss raises testosterone without any direct hormonal intervention. The relationship is self-reinforcing in both directions.
4. Lift heavy, and recover
Resistance training improves tissue response more than it raises circulating levels. Chronic overtraining without recovery suppresses production, so more is not better.
5. Cut alcohol
Suppresses testicular output directly and raises aromatase activity. Heavy intake is one of the clearest reversible causes.
6. Correct a genuine deficiency
Vitamin D and zinc raise testosterone in people who are deficient and do nothing in people who are not. Test before supplementing.
What does not work
Worth knowing before spending effort on it.
Testosterone booster supplements
Tribulus, D-aspartic acid, fenugreek and the rest do not meaningfully raise testosterone in men with normal levels. This is among the best-replicated negative findings in sports supplementation.
Zinc or vitamin D when you are replete
Correcting a deficiency helps. Taking more once corrected does not, and high-dose zinc impairs copper absorption.
Very low fat diets
Extreme fat restriction modestly lowers testosterone. This is an argument against extremes, not for eating more fat.
Self-prescribed testosterone
Effective, and a serious decision. It suppresses natural production — sometimes permanently — and affects fertility, haematocrit and cardiovascular risk. It also requires monitoring that does not exist outside clinical care.
When to involve a clinician
Low testosterone confirmed on two morning samples should be investigated rather than treated directly: pituitary causes, medication effects and sleep apnoea all present this way. Replacement is a clinical decision with fertility and cardiovascular implications.
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.
Ask Us
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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.