Life Expectancy by Lifestyle Calculator
See how smoking, activity and diet shift a rough life-expectancy estimate, adjusting a baseline by evidence-based year offsets.
How it works
estimate = baseline (81 F / 76 M) + smoking (0 / −3 former / −10 current) + activity (+4 / 0 / −3) + diet (+3 / 0 / −2) · years remaining = max(0, estimate − age)
This is a deliberately simple, illustrative model showing how a few big lifestyle factors move life-expectancy estimates. The year offsets are order-of-magnitude figures drawn from population research: lifelong smoking cuts roughly a decade off average lifespan, regular physical activity adds several years, and diet quality shifts survival meaningfully. It starts from a rough sex-based baseline and adds the offsets. Real life expectancy depends on genetics, existing conditions, income, healthcare and chance, none of which this captures — treat it as a motivator, not a forecast.
Worked example
A 45-year-old man who currently smokes (−10), is mostly sedentary (−3) but eats an average diet (0) starts from 76, adjusts by −13, and lands at about 63 years — roughly 18 more years. Quitting and becoming active would swing the estimate up by well over a decade.
Sources: Li et al., Healthy Lifestyle and Life Expectancy (Circulation 2018)
Frequently asked questions
How accurate is this?
It is illustrative only. The offsets are broad averages from population studies, and it ignores genetics, medical history and many other factors. Use it to see the relative impact of habits, not as a personal prediction.
Why does smoking cost so many years?
Large studies find lifelong smokers lose roughly ten years of life expectancy on average, and that quitting — especially before middle age — recovers much of that loss, which is why former smokers carry a smaller penalty here.
Can lifestyle changes really add years?
Yes. Research consistently links not smoking, regular activity, a healthy diet, moderate alcohol and healthy weight to several extra years and, importantly, more years in good health.
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Educational estimate only — not a medical diagnosis or a substitute for professional assessment. Screening scores and reference values are population tools; they cannot judge your individual health. Discuss any concerns with a doctor, nurse or pharmacist.