A tool to support the clinical decisions of doctors and health professionals, not for self-diagnosis or self-treatment.
This calculator is inside the patient's file in Clinicato: open it from "Medical tools" while you chart the visit, it fills in from the patient's details and vital signs where they are recorded, and adds its result to the visit's plan in one tap, with the "Medical tools" add-on. Try it in your clinic
Calculator
How it works and when to use it
Pack-years = (cigarettes a day ÷ 20) × years smoked, so a pack a day for 20 years is 20 pack-years.
The US Preventive Services Task Force (USPSTF 2021) advises yearly low-dose CT screening for lung cancer from 50 to 80 years with 20 pack-years or more, smoking now or quit within the past 15 years.
Reference: Pack-years = (cigarettes a day ÷ 20) × years; lung cancer screening: USPSTF 2021 (age 50-80, 20+ pack-years, smoking now or quit within 15 years)
Frequently asked questions
Does shisha count the same way?
No, the formula is for cigarettes only, there is no single accepted conversion for shisha, and the doctor records it separately.
Does the risk fall after quitting?
Yes, it falls gradually with the years since quitting, the most useful step for a smoker at any age.
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Clinic software for this specialty
Try Clinicato for your clinic
These calculators are free here for everyone, and in Clinicato 49 medical tools work inside the patient's file with the "Medical tools" add-on: filled from the visit and the vital signs, with the result added to the visit's plan, next to appointments, prescriptions and invoices.