What’s your biological age?

What your biological age result actually means

The number on its own isn’t the interesting part — the gap is: the distance between your biological age and the age on your passport.

It’s worth being precise about what that gap is, because it’s easy to over-read. Each answer is mapped to a published hazard ratio — how much that factor raised or lowered mortality risk in large cohort studies — and those combine and convert into years through the Gompertz mortality law. But the number you actually see is then compressed at the extremes and held consistent with your six system ages, so it never runs past your best or worst domain. That makes it a directional score: dependable about which way you’re trending and how strongly, but not a literal multiplier on anyone’s odds. An eight-year gap does not mean twice the risk of dying. Read it as a ranking against population averages, not as a probability about you.

The reveal also breaks the number down by system — cardio, metabolic, body, mobility, sleep and mind. That breakdown is the more useful half: a single weak domain is something you can actually train, where the headline figure is only a summary. And the same gap means different things at different ages.

In your 20s and 30s. A result five years older than your birthday isn’t a warning about next year — at this age the underlying risks are small in absolute terms whichever way the score lands. It’s a read on trajectory, and trajectory is the whole reason to take this early. Nearly everything driving the gap at this age (fitness, sleep, smoking, weight, alcohol) is trainable, and cheapest to change now.

In your 40s and 50s. The same gap carries more weight here, because the factors behind it have had longer to act. This is the band where a five- or eight-year gap is worth acting on rather than just noting, and where the heaviest factors in the model tend to surface for the first time: blood pressure, blood sugar, and a cardiorespiratory fitness level that has quietly drifted for a decade.

60 and over. Gaps run wider in both directions here, because decades of habits have had time to compound. A result younger than your chronological age at this point mostly reflects retained function — fitness, strength, mobility — which is the thing most closely tied to staying independent rather than merely alive.

If your result comes back younger than you are, that’s real information about the factors the quiz measured, and none at all about the ones it didn’t. It is not a screen for disease, it can’t see what’s happening inside a blood vessel, and it doesn’t mean you’re finished. The score summarises how a set of population-level associations line up for the answers you gave — it isn’t a prediction about you specifically.

And the caveat that applies to every age band: this is a questionnaire, not a measurement. It weighs what you can report about yourself. It cannot see your actual VO2 Max, HRV or body composition — the markers that predict longevity best. Take the result as a direction, then go and measure the real thing.

How is biological age calculated?

The gold standard isn’t a questionnaire — it’s measurement. The markers that predict longevity best are VO2 Max (your cardiorespiratory engine), heart rate variability (nervous-system resilience) and body composition. Population reference tables turn each marker into an “age”: if your VO2 Max matches the average 32-year-old’s, your VO2 Max age is 32, whatever your passport says.

This quiz sits one step earlier, but it’s built on the same epidemiology. Each answer you give is mapped to its published effect on the risk of dying (a hazard ratio from large cohort studies); those effects combine, and the combined risk is converted into a biological age using the Gompertz mortality law — where risk roughly doubles every eight years of adult life. It draws on 32 factors you can report without a lab. Smoking, metabolic markers (blood sugar, blood pressure), fitness and how you rate your own health carry the most weight, which matches what the mortality research consistently finds. Don’t know your blood pressure or cholesterol? Pick “not sure” and it counts as neutral — no penalty. It’s transparent — the reveal shows exactly which factors moved your number, and a biological age for each system (cardio, metabolic, body, mobility, sleep and mind) — but it is a population-average estimate, not a measurement.

Biological age vs chronological age

Chronological age is arithmetic; biological age is biology. The gap between them is the interesting number: it tells you whether your body is aging faster or slower than the calendar, and it’s one of the few health numbers you can actually train. Research on what biological age means keeps landing on the same point — fitness markers dominate, and fitness markers respond to training.

From estimate to measurement

The quiz gives you a starting point — a one-time estimate from what you can report about yourself. The Sarvita app replaces it with a measured biological age from your real VO2 Max, HRV and body composition (via Apple Health), and it keeps that number live: it updates as you train, so it’s an ongoing score you can watch move, not a snapshot you take once. From there Sar, your AI coach, puts you on your Longevity Path — a weekly plan across five pillars (cardio, strength, nutrition, stability and sleep) that starts with the areas ageing you most, guiding you one pillar at a time and tracking the number as it drops. See the four pillars of longevity for the science behind the plan.