Pack Year Calculator
Calculate smoking pack-years from cigarettes per day and years smoked. Free and private.
Independently verified for accuracy
Calculator by Toolsloft ↗- Pack-years
- 10
Calculate smoking pack-years, the measure clinicians use to gauge lifetime tobacco exposure. Enter how many cigarettes you smoke per day and for how many years. One pack equals 20 cigarettes, so 20 a day for a year is one pack-year.
How this is calculated
Pack-years equal cigarettes per day divided by 20 (the number of cigarettes in a pack) multiplied by the number of years smoked. This is the standard definition used in medical screening, for example when assessing lung cancer risk.
How to use
- Enter the average number of cigarettes you smoke per day.
- Enter the number of years you have smoked.
- Read your total pack-years.
Examples
- 20/day for 10 years:
10 pack-years - 10/day for 15 years:
7.5 pack-years
FAQ
- Why does one pack-year equal 20 a day for a year?
- A standard pack holds 20 cigarettes. Smoking one pack (20 cigarettes) per day for one year is defined as one pack-year, and the formula scales from there.
- What if my smoking changed over the years?
- Use your typical daily amount. For very different periods, calculate each period separately and add the pack-years together.