One of these is a single lab value. The other is that exact same lab value, run through a short formula with one more number from the same blood draw. The question worth answering is when that extra step earns its place.
| HOMA-IR | fasting insulin | |
|---|---|---|
| What it measures | A calculated index combining fasting insulin and fasting glucose | Fasting insulin on its own, directly from the lab |
| Formula | Insulin (µIU/mL) × glucose (mg/dL) ÷ 405 | — a single reported value, no calculation |
| Extra blood draw required | No — uses the fasting glucose already on a routine panel | No, but most labs do not run it automatically; it typically has to be requested |
| Most informative when | Glucose itself has started drifting upward, alongside insulin | Glucose is still normal — this is usually where insulin resistance first shows up |
| Threshold used here | <1.0 good; 1.0–1.9 reasonable middle; >2.0 insulin resistance; >2.9 substantial (exact cut-points are lab- and population-dependent) | Scored against a longevity-optimised band, tighter than the roughly 25 µIU/mL standard lab ceiling |
| Scored directly on this dashboard | No — calculated and shown for context, to avoid double-counting the same physiology | Yes — on the metabolic dial |
HOMA-IR is not a separate test. It is fasting insulin (in µIU/mL) multiplied by fasting glucose (in mg/dL), divided by 405 — or divided by 22.5 if glucose is reported in mmol/L. Both inputs have to come from the same genuinely fasted draw, typically 8–12 hours. Fasting insulin is simply one of those two ingredients, reported on its own.
This calculator computes HOMA-IR automatically whenever both values are entered, and a standalone HOMA-IR calculator is also available for a quick check from any two lab values.
In people whose fasting glucose is still comfortably normal — which is most people with early insulin resistance — HOMA-IR and fasting insulin track each other closely. The formula's second input, glucose, is not moving much yet, so it contributes little beyond what insulin alone already shows. In that situation, the extra arithmetic adds very little real information.
The formula earns its place once glucose itself starts to rise. At that point, HOMA-IR captures a combination that neither input shows on its own: a system that is both working harder (elevated insulin) and starting to lose the fight (elevated glucose) is in a meaningfully different position from one that is only working harder while still succeeding. Two people with identical fasting insulin can have different HOMA-IR scores if their fasting glucose differs, and that difference is informative.
Fasting insulin and fasting glucose are both already scored individually on the metabolic dial. Scoring HOMA-IR as a third, separate input would count the same underlying physiology twice, inflating its apparent weight in the composite. HOMA-IR is calculated and displayed for context — it is a genuinely useful number to look at — but deliberately left out of the point scoring for that reason.
If you can only track one number reliably over time, fasting insulin alone is usually sufficient, particularly while glucose remains normal — which is the exact window where catching insulin resistance early matters most. Once glucose starts moving as well, start paying closer attention to HOMA-IR specifically, since that is the situation its extra arithmetic was built to describe. In practice, since both numbers come from the same blood draw, there is little reason to track only one: ask for fasting insulin on your panel, and let a quick calculation — or this calculator — handle the rest.
Not uniformly. The two track closely while fasting glucose remains normal, which is most early insulin resistance. HOMA-IR adds real information specifically once glucose has also started to rise, because it captures that combination directly.
Yes, though it is less common than the two agreeing. Because HOMA-IR depends on both values, an unusual combination of insulin and glucose can occasionally push the calculated index in a direction one input alone would not suggest. When the two disagree, it is worth looking at both numbers individually rather than trusting the combined index alone.
Multiply fasting insulin (µIU/mL) by fasting glucose (mg/dL) and divide by 405 — both values must come from the same fasted blood draw. This site's own HOMA-IR calculator does the arithmetic directly from your two lab values.
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Not uniformly. The two track closely while fasting glucose remains normal, which is most early insulin resistance. HOMA-IR adds real information specifically once glucose has also started to rise, because it captures that combination directly.
Yes, though it is less common than the two agreeing. Because HOMA-IR depends on both values, an unusual combination of insulin and glucose can occasionally push the calculated index in a direction one input alone would not suggest. When the two disagree, it is worth looking at both numbers individually rather than trusting the combined index alone.
Multiply fasting insulin (µIU/mL) by fasting glucose (mg/dL) and divide by 405 — both values must come from the same fasted blood draw. This site's own HOMA-IR calculator does the arithmetic directly from your two lab values.
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.