About
Longevity research you can measure at home
How Old Is Your Body? is a free, independent tool that turns large population studies into a biological age, and shows you which changes would move it most.
Why it exists
Some of the strongest predictors of a long life aren’t found in a lab. How easily you get up off the floor, how long you can stand on one leg, and how fast you walk each say a lot about your future health, and you can measure all of them at home in a few minutes.
That research rarely reaches the people it could help. This site gathers it into one free tool, shows you exactly where every number comes from, and points you to the changes that matter most for you.
Physician-built
The test was designed by a practicing hospital medicine physician who spends every day helping patients and families make decisions about their care. The model, sources and limitations are all published on the science page for anyone to review.
Our principles
- Independent. No sponsors shape what we publish, and there’s nothing to sell you.
- Transparent. Every formula and source is public.
- Honest about uncertainty. We show ranges and limitations, not false precision.
- Private by default. We don’t collect what we don’t need.
Privacy
The test runs entirely in your web browser. The answers you enter are stored only on your own device, using your browser’s local storage, so they’re there when you return. They are never sent to us or anyone else. Clearing your browser data, or pressing “Clear all” on the test, erases them.
This site loads fonts from Google Fonts, which receives standard web request information such as your IP address. We don’t use advertising trackers.
Medical disclaimer
This site is for education only. It isn’t medical advice, a diagnosis, or a substitute for care from a qualified clinician, and it doesn’t account for diagnosed conditions, medications or family history. If you have symptoms or health concerns, talk with your doctor.