Frequently asked questions

It’s a population-level estimate, not a measurement of your cells. It tells you how your measures compare with large groups of people whose outcomes were tracked for years. Two people with identical numbers can have very different futures, which is why we show a middle-50% range rather than a single age of death.

Treat it as a direction and a size: are you ahead or behind, and by roughly how much?

Biological age is the age whose average yearly risk of death matches yours today. Life expectancy is the average age people with your profile would reach if your measures stayed where they are. Both come from the same model.

Because in the study it comes from, it was one of the strongest single predictors of survival: people scoring 0 to 3 had about five times the mortality of those scoring 8 to 10. It also improves with practice, so it’s often one of the most rewarding things to work on.

No. Diagnosed conditions like heart disease, cancer, diabetes or kidney disease can change life expectancy far more than anything the test measures. If you have one, your clinician’s assessment matters more than this estimate.

Enter your current treated reading. Well-controlled blood pressure carries much lower risk than untreated high blood pressure, and your treated number is the best reflection of that.

Reasonably. Most watches estimate within about 10% of a lab test for people who run or walk outdoors regularly with GPS. It’s usually more accurate than the resting-pulse formula, so use it if you have it.

For most people, yes; they’re everyday movements. Have someone nearby for the balance and sitting-rising tests, use a counter for support if you need to, and stop if anything hurts. Skip the step test if you have heart disease, chest pain with exertion, or trouble with balance. If you’re pregnant, recovering from surgery, or have joint problems, check with your clinician first.

Leave it blank. Blank measures count as typical for your age and sex, so they neither raise nor lower your result. For the chair stands, there’s a separate option if you can’t complete them without using your arms, because that is meaningful information.

Partly. The habit and vitals measures are well studied in younger adults. Most of the physical tests were studied in people over 50, so for younger adults those results are extrapolations. A strong result still reflects fitness you’ll carry into later life.

Every three to six months is enough to see real change. Strength, balance and fitness respond to training within weeks; body composition and blood pressure take a little longer.

Nowhere. The test runs entirely in your browser. Your answers are saved only on your own device, so they’re there when you come back, and you can erase them anytime with “Clear all.” We never receive them.

Yes. There’s no account, no paywall, and nothing to sell you at the end.

Yes, if it’s useful. The “Print summary for your doctor” button on the test page produces a one-page summary of your measurements, your top areas to improve, and a few questions to ask. It’s a conversation starter, not a diagnosis.

The test lists your three biggest opportunities, ranked by how much each could lower your biological age. For most people, it’s one of strength and balance, aerobic fitness, waist size, or smoking.