Smoking Pack Years

One pack year is 20 cigarettes a day for one year. Working that out by hand is awkward when someone has smoked different amounts, or different types of tobacco, over the years. The calculator does the sum for them, and was highly commended for Best use of Media and Technology in the GP Enterprise Awards 2012. It was built for clinicians at a desktop, but lung cancer screening now brings patients to the site too, often on a phone.

In October 2026 we rebuilt the site with a new mobile-friendly design, in the same style as Dr Masters’ other site, Clinical Indications. The calculator now works step by step: tick the types of tobacco smoked, enter how much and for how many years, and add another period whenever the amount changed. A running total updates as you go and the result shows a breakdown by tobacco type. It works out pack years in exactly the same way as the original calculator, which we checked against the old version across 20,000 test cases.

Results can be downloaded as a PDF, emailed, printed or saved as a link. Nothing typed into the calculator is kept: answers stay in the browser, and a PDF or email is made once and then discarded. A clinician mode gives a line to paste into EMIS or SystmOne, and an embed code lets other organisations put the calculator on their own websites.

New pages explain what a pack year is, help people invited to a lung health check work out their smoking history, and give GPs, nurses and screening teams their own guidance. The References page shows the cigarette equivalents the calculator uses, from a cigar or spliff counting as four cigarettes to a 20-minute waterpipe session counting as 25, with links to the sources. An AI chat assistant answers visitors’ questions about the calculator, and analytics only load once a visitor accepts cookies.