Pack-Years Calculator
Calculate your smoking pack-years in one step
Result
How to use
- Enter your values in the fields above.
- Press Calculate to see your result instantly.
- Use the Share button to copy a link to your result.
About this calculator
A pack-year equals one pack (20 cigarettes) smoked per day for one year: pack-years = (cigarettes per day ÷ 20) × years smoked. Someone who smoked a pack a day for 20 years has the same 20 pack-year exposure as someone who smoked two packs a day for 10 years, even though their daily habits look very different.
Pulmonologists and primary care doctors use pack-years to quantify cumulative tobacco exposure and estimate lung cancer and COPD risk. It's also the exact threshold in clinical guidelines — the USPSTF recommends annual low-dose CT lung cancer screening for current or former smokers with at least a 20 pack-year history who are within 15 years of quitting.
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