Pack Year Calculator
Estimate total smoking exposure from cigarettes per day across one or more periods.
Calculate your smoking pack-years
Calculate smoking pack-years from cigarettes per day and years smoked using the standard clinical exposure formula.
Formula used
Pack-years = (cigarettes per day ÷ 20) × years smoked. Enter cigarettes per day directly. The default pack size is 20 cigarettes; change it if the packs you used contained a different number.
Worked example
Ten cigarettes per day for 20 years equals 0.5 packs per day × 20 years = 10 pack-years.
Make the result more accurate
If consumption changed, calculate each period separately and add the results. Pack-year values describe exposure history and do not diagnose disease or determine an individual risk by themselves.
Useful next steps
Calculate smoking cost · Review medical sources · Build a quit plan
Frequently asked questions
What is one pack-year?
One pack-year means an average of one 20-cigarette pack per day for one year.
How do I handle changing smoking amounts?
Calculate each period separately, then add the pack-year values.
Is a pack-year result a diagnosis?
No. It is an exposure measure used alongside clinical assessment.
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