Pack Years Calculator
Calculate cigarette smoking exposure in pack-years.
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Packs per day
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Years
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Pack-years
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About
Pack-years summarize cumulative cigarette exposure as average packs smoked per day multiplied by years smoked. The default conversion assumes 20 cigarettes per pack and can be adjusted for a different pack size. The value does not by itself determine eligibility for lung-cancer screening.
Formula
Interpretation
Use: Enter an average exposure for the period represented. If smoking intensity changed substantially, calculate each period separately and add the results.
Screening context: Screening criteria also depend on age, current versus former smoking, time since quitting, health status, and the guideline used.
Worked example: 15 cigarettes/day for 20 years with 20 cigarettes/pack equals 0.75 packs/day × 20 = 15 pack-years.
FAQ
Disclaimer
Educational and informational reference only. Not intended to replace professional medical advice, diagnosis, treatment, or independent verification.