Your baseline comes from the US Social Security Administration Period Life Table (2021) — the same actuarial table used for Social Security. Lifestyle answers then add or subtract years using published studies (smoking: NEJM 2013; exercise: PLOS Medicine 2012; sleep, diet, alcohol and more), converted with the standard Gompertz mortality model (Spiegelhalter, BMJ 2012). Every factor shows its source.
No death clock can predict an individual's death — this one reports the statistical life expectancy for someone with your profile, which is the honest version of the answer. Roughly half of people outlive their estimate. Treat it as a planning number and a motivator, not a prophecy.
In the underlying studies: not smoking (about 10 years versus a current smoker), regular exercise (up to ~4 years), 7–8 hours of sleep, moderate alcohol, and daily movement. The quiz shows the years attached to each answer as you go.
No. It is a statistics-based educational tool. For anything about your actual health, see a clinician.