How old is your body, really?
Eight questions, then your biological age and the one change that buys back the most.
Your age, then eight taps.
0 of 81Smoking
2Movement
3Sleep
4Blood pressure
5Weight
6Alcohol
7Fruit and vegetables
8People
Biological age estimates how worn your body is next to the years since you were born. Eight questions, and only two of them carry the figure. Nothing is stored and no account is needed. How blood and DNA tests compare .
What the number is built from
Smoking, graded by your age. More than 200,000 US adults linked to the National Death Index. Smokers lost at least ten years. Quitting regained almost all of them at 25 to 34, about nine at 35 to 44, six at 45 to 54, four at 55 to 64. That is why the same answer moves a 28 year old ten years and a 68 year old two. Jha et al, NEJM, 2013.
Movement. 654,827 people pooled across six cohorts, 82,465 deaths, a median of ten years each. Life expectancy after 40 ran 1.8 years higher at up to 75 minutes of brisk walking a week, 3.4 years at 150 to 299, and 4.5 above that. Under 40 the study cannot speak for you, and the tool says so rather than applying it quietly. Moore et al, PLOS Medicine, 2012.
The half nobody quotes: six of the eight cannot claim years. Sleep, blood pressure, weight, alcohol, food and company are real risks with no life expectancy table behind them. Together they move the answer by at most three years either way, so either measured factor outweighs all six. This is arithmetic on population averages. Nothing is read from your cells. How blood and DNA tests compare.
Every figure on this site names where it came from. How we check.
What your gap means
| Health age against your age | What it means | What moves it most |
|---|---|---|
| 5 or more years younger | The habits with the strongest evidence are in place. Rare without regular movement and no smoking. | Keep it. Retake once a season. |
| 1 to 4 years younger | Common in non-smokers who move most days. The gap says direction, not destiny. | Sleep and blood pressure are usually what is left. |
| About the same | Average for your age. Nothing is pulling hard either way. | 150 minutes of brisk walking a week, if it is not there yet. |
| 1 to 4 years older | One or two answers are costing years, usually sitting most days or short sleep. | The single weakest answer. Fix one, retake in three months. |
| 5 to 9 years older | Nearly always smoking, or no movement at all, or both. | Quitting, which regains most of the gap at any age under 65. |
| 10 or more years older | Smoking plus another risk. This is the range where the arithmetic matches the mortality tables. | Quitting first. Then walking. Then a doctor, for blood pressure. |
Common questions
How old am I biologically?
Biological age estimates how worn your body is next to the years since you were born. This calculator asks eight questions, and two of them carry the figure: smoking and movement, the two with published life expectancy numbers behind them. Smoking is graded by age, because the evidence is. Across more than 200,000 US adults, quitting regained about ten years at 25 to 34 and about four at 55 to 64. The other six move the answer by at most three years either way. Two minutes.
What's the difference between biological age and my real age?
Your birthday counts years. Biological age estimates wear. A 50 year old who moves daily, sleeps seven hours and keeps blood pressure in range can score younger than a sedentary 35 year old, because the habits that drive most of the preventable difference in lifespan are not the same thing as time passing. It is an estimate for direction, not a diagnosis.
What is a good biological age?
A good biological age is one below your calendar age, and the size of the gap matters less than the direction it moves. Scoring one or two years under is common in people who do not smoke and move regularly. What the number is for is comparison with your own previous result, not with other people, because the inputs and the weightings differ between every calculator on the internet.
Is there an NHS biological age calculator?
No, the NHS does not offer a biological age calculator. Its nearest tool is the heart age calculator, for UK adults aged 30 to 95 without heart disease, which uses weight, height and, if you know them, blood pressure and cholesterol to compare your heart age with your real age. This calculator asks a wider question: how your habits compare with your birthday.
Is this as accurate as a biological age blood test?
No, and it does not pretend to be. Epigenetic clocks and blood-marker tests measure biology directly, though they are noisier for one person than their marketing suggests. This calculator does arithmetic on known risk factors instead. The trade is honesty about the method: every input is something you can see and change, which a methylation score is not.
How do I lower my biological age?
For a smoker, quitting, by a wide margin. After that the largest and best-evidenced gains are the step from no exercise to regular brisk walking, treating untreated high blood pressure, and fixing chronically short sleep. Each of those moves this score, and each of them moves real risk in the studies the score is built on.
How often should I retake it?
Once a season is about right. Habits take weeks to show up as a changed answer, and retaking it weekly measures your mood rather than your health. Taking it, spending a month on the single weakest answer, and retaking it is the loop the number is designed for.
Want the real numbers behind the estimate?
The Health Review reads your labs, history and lifestyle together and maps your risk over the next ten years, in writing.