Pack-Years Calculator
A free, browser-based calculator. Runs entirely in your browser — no sign up, nothing stored.
100% FreeRuns in your browserBasic
Enter Values
Enter your values and press Calculate to see results.
How to use this calculator
- Enter cigarettes per day and years smoked.
- Read the pack-years.
How it works
Pack-years = (cigarettes per day ÷ 20) × years smoked.
Worked example
20/day for 10 years. = 10 pack-years.
Common mistakes
- Assuming a pack is always 20 — adjust if yours differs.
- Averaging unevenly — use your typical daily amount.
Frequently asked questions
Why do clinicians use pack-years?
It standardises smoking history into one number to help assess risk. This tool is educational, not medical advice.
Related tools
Tip: Enter any known values to calculate the remaining results.
All calculations run in your browser. Your inputs are never saved or transmitted.