Pack-Year Smoking History
Converts cigarettes per day and years of smoking into pack-years.
When to use
Quantification of cumulative smoking in adults for respiratory and cardiovascular risk assessment.
Pearls and pitfalls
- One pack-year equals 20 cigarettes per day for one year.
- Pack-years do not capture time since quitting or recent intensity.
- The calculation is a retrospective estimate and depends on patient recall.
- Use the same local pack size when converting cigarettes per day.
Fill in the fields to see the result.
Formula
Pack-years = (cigarettes per day / 20) × years of smoking.
Evidence
Definition standardized by the National Cancer Institute to express cumulative tobacco exposure.
References
- National Cancer Institute. NCI Dictionary of Cancer Terms: pack year. https://www.cancer.gov/publications/dictionaries/cancer-terms/def/pack-year
Frequently asked questions
What is Pack-Year Smoking History?
Converts cigarettes per day and years of smoking into pack-years. Quantification of cumulative smoking in adults for respiratory and cardiovascular risk assessment.
How is the result calculated?
Pack-years = (cigarettes per day / 20) × years of smoking.
How should the result be interpreted?
Definition standardized by the National Cancer Institute to express cumulative tobacco exposure.
What are the sources?
National Cancer Institute. NCI Dictionary of Cancer Terms: pack year.