Pack-Years Calculator

About this calculator

This calculator multiplies packs smoked per day by years smoked to produce a "pack-year" figure (one pack-year equals smoking a full pack a day for one year) — the standard clinical measure doctors use to quantify cumulative cigarette exposure, since it captures both intensity and duration in one number rather than either alone.

Physicians use pack-years to assess a patient's risk for lung cancer and COPD and to determine eligibility for low-dose CT lung cancer screening (US guidelines generally require 20+ pack-years for eligibility), and patients filling out a medical history form use it to answer the "how much have you smoked" question with the specific figure doctors expect rather than a vague description.