Smoking: Cost | Loss of Lifespan

Estimating Loss of Lifespan Due to Smoking

Calculator for the years and months of life lost depending on smoking intensity.

This is a very simplified estimate for the reduced life expectancy of smokers. It ignores many factors, but still provides reasonable average values. Further factors that influence the actual loss of lifespan are not considered here and would make such a calculation significantly more complex or even impossible. These include genetic factors, sex, age at starting, exact ingredients of the cigarettes, other lifestyle factors, medical care, and of course simple chance. Therefore, the value calculated here should not be considered a certainty and is only a rough estimate. Even with consideration of additional factors, individual variation would be large.

Please enter the average number of cigarettes smoked per day and the number of years of smoking. From these values, pack-years (PY) are calculated using the formula PY = n*y/20. If you already know the pack-years, you can enter that directly. Age at cessation plays an important role — the earlier, the better. If you never quit, leave this field empty.

Cigarettes per day (n):
Years of smoking (y):
Pack-years (PY):
Age at cessation (a):

Lifespan lost: years, months

Cessation factor f:
(between 0 and 1, the smaller, the better)

Example: 20 cigarettes per day for 20 years leads to an expected reduction in lifespan of about three and a half years (3 years, 6 months) if quitting at age 40. If quitting only at 60, it is 6 years and 10 months. However, with the same starting age, the smoking duration is longer then. If someone smokes now for 40 years, this results in a calculated life expectancy that is 9 years and 4 months shorter.

The factor f is calculated as f = 1 / (1 + e^( -0.2 * (a - 40) ) ). This was heuristically chosen as a sigmoid function to approximate the trends from the data. The calculation of reduced lifespan is a mathematical approximation based on empirical values. The formula for life years lost is 11 * ( 1 - e^( -0.05 * PY ) ) * f.

Note: these formulas were created using artificial intelligence from aggregated summaries of epidemiological study data. They have not been published in scientific journals.
This tool does not replace medical advice. The calculations are for informational purposes only. Decisions regarding smoking, health, or medical interventions should not be made solely based on this calculator. For personalized guidance, please consult a healthcare professional. No personal data is stored or shared.

References for Studies on Smoking and lifespan Loss

1. British Doctors Study:
   Doll, R., Peto, R., Boreham, J., & Sutherland, I. (2004). Mortality in relation to smoking: 50 years’ observations on male British doctors. BMJ, 328, 1519. Link to study
   Note: Lifetime heavy smokers lose about 10 years of life. Basis for pack-year interpretation.
2. CPS-II Study (American Cancer Society):
   Thun, M. J., et al. (2013). 50-year trends in smoking-related mortality in the United States. New England Journal of Medicine, 368, 351–364. Link to study
   Note: Large US cohort; data on cigarettes/day, duration, cessation, and mortality.
3. Meta-analysis on cessation and lifespan:
   Jha, P., et al. (2013). 21st-century hazards of smoking and benefits of cessation in the United States. New England Journal of Medicine, 368, 341–350. Link to study
   Note: Quantifies lifespan gain from cessation at different ages.
4. Popular summaries:
   The Guardian (2024). Single cigarette takes 20 minutes off lifespan – study. Link to article
   Note: Summary of epidemiological data; useful for rough estimates, not an original publication.

Last updated on 03/23/2026. Author: Jürgen Kummer

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