Doctors measure smoking history in pack-years. Enter how much and how long you have smoked to get your pack-years and see whether yearly lung screening is recommended.
Fill in the details and click Calculate to see your results.
One pack-year means smoking 20 cigarettes (one pack) a day for a year. 10 a day for 20 years is also 10 pack-years. The higher the number, the higher the risk of lung cancer, COPD and heart disease.
The US Preventive Services Task Force recommends a yearly low-dose CT scan for people aged 50–80 with 20 or more pack-years who smoke now or quit within the last 15 years. A 2024 UCL study found each cigarette shortens life by about 20 minutes on average.
| Cigarettes or bidis a day | 20 a day |
| Years smoked | 30 years |
| Your age | 55 years |
| Do you smoke now? | Yes, I smoke |
| Years since you quit | 0 years |
| Pack-years | 30.0 |
| Cigarettes smoked in all | 219,000 |
| Life expectancy lost (estimate) | 8.3 years (about 20 minutes per cigarette) |
| Lung cancer screening (USPSTF) | Eligible — yearly low-dose CT scan is recommended; ask your doctor |
| Risk band | Heavy smoking history |
30.0 pack-years; Eligible — yearly low-dose CT scan is recommended; ask your doctor.
| Cigarettes or bidis a day | 10 a day |
| Years smoked | 15 years |
| Your age | 40 years |
| Do you smoke now? | Yes, I smoke |
| Years since you quit | 0 years |
| Pack-years | 7.5 |
| Cigarettes smoked in all | 54,750 |
| Life expectancy lost (estimate) | 2.1 years (about 20 minutes per cigarette) |
| Lung cancer screening (USPSTF) | Not in the screening group (needs 20+ pack-years; for ages 50–80) |
| Risk band | Light |
7.5 pack-years; life lost 2.1 years (about 20 minutes per cigarette).
Pack-years = (cigarettes a day ÷ 20) × years smoked. For example 15 a day for 20 years = 0.75 × 20 = 15 pack-years.
Yes — count each bidi as one cigarette. Bidis deliver as much or more tar and carbon monoxide than cigarettes.
There is no fixed cut-off, but 20+ pack-years is the screening threshold and is often used to describe a heavy smoking history.