The Independence Number
is the one nobody gave you.
How much strength and balance do you need today to still be doing things for yourself at 85?
Fifteen minutes. A chair and a tape measure. No signup — you see your results first.
I'm 47, two young kids, and I have spreadsheets for retirement. I know what I need saved by 55.
Then I started asking how long I'll be able to do things for myself. Driving. Stairs. Getting off the floor without a hand. I couldn't find a number, so I read the research and built this.
It won't predict your lifespan and it won't give you one score — no published method exists for combining these tests. Every row shows how strong its own evidence is.
What a result looks like
SAMPLE · man, 47, at the published median for his age · target age 85
| Row | Your value | Range for 47 | Need today for 85 | Evidence | State |
|---|---|---|---|---|---|
| Gait speed | 1.43 m/s | 1.30–1.57 · 50th pct | 1.63 | strong · 51,000 people | ● Behind by −0.20 |
| Aerobic capacity | 33.7 mL/kg/min | 28–41 · 50th pct | 34.4 | strong · 16,278 tests | ● Behind by −0.70 |
| Sitting-rising | 8 of 10 | ≥ 8 | 8 | limited · one clinic | ✓ On track by +0.0 |
Six more rows on the full panel.
Every number above is a published median for a 47-year-old man. Not a real person — and not a flattering picture. Average is already behind.
The argument, at length
Why the number exists, and where the research behind it gets quoted wrongly.