Pack Year Calculator
Smoking history in pack years.
Enter your values
Enter the cigarettes per day you are working with.
Enter the years smoked you are working with.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Pack years
- 16.5
- Total cigarettes
- 120,450
- Screening eligible (US 20+)
- Not by pack years alone
- Packs consumed
- 6,023
Quick answer
One pack year equals smoking 20 cigarettes a day for a year; 20+ pack years usually triggers screening eligibility.
Pack years = (Cigarettes/day ÷ 20) × Years
At a glance
| What it does | Smoking history in pack years. |
|---|---|
| Category | Health |
| Inputs needed | Cigarettes per day, Years smoked |
| Main output | Pack years |
| Formula | Pack years = (Cigarettes/day ÷ 20) × Years |
| Cost | Free — no sign-up, no download |
How to use the Pack Year Calculator
- 1Enter your average cigarettes per day.
- 2Enter total years smoked.
- 3Compare with the 20 pack year screening threshold.
Inputs explained
- Cigarettes per day
- Enter the cigarettes per day you are working with.
- Years smoked
- Enter the years smoked you are working with.
Worked example
Using the values the calculator loads with:
Inputs
- Cigarettes per day15
- Years smoked22
Results
- Pack years16.5
- Total cigarettes120,450
- Screening eligible (US 20+)Not by pack years alone
- Packs consumed6,023
Frequently asked questions
What if my habit varied?
Average across periods, or add pack years for each period separately.
Does quitting reset it?
No, pack years are cumulative, but risk does fall after quitting.
What do I need to enter into the Pack Year Calculator?
Just 2 values: cigarettes per day, years smoked. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Pack Year Calculator work out the answer?
One pack year equals smoking 20 cigarettes a day for a year; 20+ pack years usually triggers screening eligibility. It applies the formula Pack years = (Cigarettes/day ÷ 20) × Years and shows the working so you can check each step by hand.
Is the Pack Year Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.