Pack-year calculator

A pack-year is one pack a day for one year. It is the standard way clinicians quantify smoking history, and it decides eligibility for some screening programs - so knowing your number is genuinely useful.

A US pack is 20 cigarettes. Estimate an average across the years.
Total years, minus any long breaks.

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Why this number exists

"How much did you smoke?" is a hard question to answer usefully - amounts change over decades. Pack-years compress the whole history into one comparable number: cigarettes per day, divided by 20, multiplied by years smoked. Ten cigarettes a day for twenty years and a pack a day for ten years are both 10 pack-years.

What it is used for

The US Preventive Services Task Force recommendation on lung cancer screening uses pack-years as an eligibility criterion, alongside age and how recently someone smoked. Whether screening is appropriate for you is exactly the kind of individual decision this site does not make - but walking into the appointment already knowing your pack-years turns a vague conversation into a specific one.

Questions worth taking with the number:

  • Given my pack-years and my age, do I meet the current criteria for lung cancer screening?
  • Is the screening covered by my plan as a preventive service?
  • If I quit years ago, does that change whether screening applies to me?

Preventive services are frequently covered without cost sharing at in-network providers - our guide on how cost sharing works explains the mechanics, and it is always worth confirming coverage before booking.

Where this comes from

The USPSTF lung cancer screening recommendation: uspreventiveservicestaskforce.org.

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