Smoking Pack Years Calculator
Calculate your total pack-years of smoking history — a key clinical metric used in lung cancer screening eligibility and COPD risk assessment.
Use the Smoking Pack Years Calculator
Smoking History
Add one or more smoking periods. Leave years as 0 for a period you have not yet completed.
Enter your smoking history and click Calculate to see results.
Period Breakdown
How It Was Calculated
Pack-years = (cigarettes per day ÷ 20) × years smoked. Each period is calculated independently and the totals are summed. 20 cigarettes = 1 standard pack.
This calculator is for informational purposes only and does not constitute medical advice. Consult a qualified healthcare provider for screening decisions and medical guidance.
Summary
Pack-years is a standardized clinical measure of cumulative tobacco exposure calculated by multiplying the number of cigarette packs smoked per day by the number of years you have smoked. One pack-year equals smoking one pack (20 cigarettes) per day for one year, or two packs per day for six months. Clinicians use pack-year history to determine eligibility for low-dose CT lung cancer screening (typically 20+ pack-years) and to stage COPD severity.
How it works
- Enter the average number of cigarettes you smoke (or smoked) per day.
- Enter how many years you have smoked at that rate.
- Optionally add additional smoking periods with different cigarette counts.
- The calculator divides cigarettes per day by 20 to get packs per day, then multiplies by years smoked.
- Total pack-years are summed across all periods and displayed instantly.
- Review the clinical risk tier and screening guidance based on your result.
Use cases
- Determine eligibility for low-dose CT (LDCT) lung cancer screening.
- Provide accurate smoking history to a healthcare provider or specialist.
- Assess COPD risk and staging based on cumulative tobacco exposure.
- Track how quitting reduces effective future pack-year accumulation.
- Complete pre-operative or insurance smoking history questionnaires.
- Educate patients about the clinical significance of their tobacco history.
- Calculate combined pack-years from multiple quit-and-restart periods.