Pack-year calculator
Estimate smoking history and lung cancer screening eligibility
This calculator is for educational purposes only. Pack-year calculations help assess lung cancer screening eligibility.
Always consult your healthcare provider for personalized medical advice and screening recommendations.
Calculate pack-years
Enter your smoking history to calculate pack-years
Understanding pack-years
What are pack-years?
Pack-years is a standardized way to measure cigarette smoking history. It combines the number of packs smoked per day with the number of years a person has smoked. This measurement helps healthcare providers assess lung cancer risk and determine screening eligibility.
Why pack-years matter for cancer screening
Lung cancer screening guidelines often use pack-year history as a key criterion. The U.S. Preventive Services Task Force (USPSTF) recommends annual lung cancer screening with low-dose CT for adults aged 50-80 who have a 20 pack-year smoking history and currently smoke or have quit within the past 15 years.
How to calculate pack-years
The formula is simple:
Pack-years = (Number of packs per day) × (Years smoked)
For example, if someone smoked 1.5 packs per day for 20 years, their pack-year history is 30 pack-years (1.5 × 20 = 30).
Pack-year risk levels
- 30+ pack-years: High risk - strongly consider screening discussion with your doctor
- 20-29 pack-years: Moderate-high risk - screening may be recommended based on age and other factors
- 10-19 pack-years: Moderate risk - discuss with healthcare provider
- Under 10 pack-years: Lower risk, but not risk-free
Other factors that affect lung cancer risk
Besides pack-years, several other factors influence lung cancer risk:
- Age (risk increases with age)
- Family history of lung cancer
- Exposure to radon, asbestos, or other carcinogens
- Chronic lung diseases like COPD
- Environmental tobacco smoke exposure
Benefits of quitting smoking
Quitting smoking at any point reduces lung cancer risk over time. Within 5-10 years after quitting, lung cancer risk drops significantly. Former smokers may still qualify for screening based on their pack-year history and time since quitting.
When to talk to your doctor
If you have a significant smoking history (especially 20+ pack-years), are between 50-80 years old, and currently smoke or quit within the past 15 years, talk to your healthcare provider about lung cancer screening with low-dose CT scanning.