Work out a patient's smoking history in pack-years
Enter packs or cigarettes per day and the years smoked, for as many periods as the history has. Get the total in pack-years.
Pack-years are packs per day times years smoked, with 20 cigarettes to a pack, added up across periods.
Total
25 pack-years
Packs per day times years for each period, added together. A pack is counted as 20 cigarettes.
| Period | Packs per day | Pack-years |
|---|---|---|
| Period 1 | 0.5 | 5 |
| Period 2 | 1 | 20 |
How it works
Understand the result
Count one pack a day for a year as one pack-year
Ten cigarettes a day for 20 years is also ten pack-years. The unit lets you compare histories that differ in rate and length.
Enter every smoking period
People cut down, stop and start again. Enter each period on its own line and the calculator adds them up.
Record what the figure leaves out
Pack-years do not capture cigars, pipes, rolled tobacco, vaping or the years since stopping. Record those alongside the number.
Use the result to support your judgment
A calculator gives a number from the inputs you type. It knows nothing else about the patient, and it does not replace clinical judgment or local guidance.
In a workup
Record the history in the patient workspace
Add the smoking history to the patient's notes in Workup Desk. When you draft a clinical assessment or a referral letter, the draft includes the pack-years from that note. You review the draft before you file it.
See assessment draftingQuestions
Frequently asked questions
How do I count hand-rolled cigarettes?
There is no single agreed conversion. Count each one as a cigarette and note the type next to the figure.
Does stopping reduce the pack-years?
No. Pack-years measure exposure to date. Record the year the patient stopped as a separate fact.