Working out your smoking history

What is a pack year?

A pack year is the same as smoking 20 cigarettes a day for one year. Cigars, roll-ups, pipes and other tobacco are converted into cigarettes so that everything can be added up. See what a pack year is.

What should I note down before I start?

Think back over the years you smoked. Best guesses are fine. For each type of tobacco, note:

• What you smoked: cigarettes, cigars, cigarillos, spliffs, bidis, a pipe, loose tobacco or a waterpipe (shisha). Roll-ups count as loose tobacco.
• How much: the number a day, or bowls a day for a pipe. Loose tobacco is the weight used each week, in grams or ounces. A waterpipe is the number of 20-minute sessions a week.
• For how many years you smoked that amount.
• Any changes: note each amount as a separate period. If you stopped and started again, leave out the years when you had stopped.
• Whether you still smoke and, if not, the year you stopped (and the month, if you know it).
• How many years you smoked in total. If you smoked different types at the same time, count those years once.

How can I remember what I smoked years ago?

The FAQs suggest recalling what you smoked in each decade of your life. See the decade-by-decade method.

How do I use the calculator?

1. Open the calculator and choose Me (the instructions go through each step). Invited to a lung health check? Use the version on the lung health check page.
2. Tick everything you have smoked regularly at any time in your life.
3. For each type, enter how much and for how many years. Choose Add another period if the amount changed.
4. Answer the optional history questions, or skip them.
5. Choose See my result.

The result shows your total in pack years, the figure before rounding if it differs, and how it adds up for each type. What your result means explains the number, and changing smoking habits covers cutting down, stopping and restarting.

What should I take with me?

On the result screen you can:

• Download PDF to keep a copy.
• Print the result.
• Email me the PDF to send it to yourself.
• Save or share a link. Your answers are inside the link itself, so anyone you give it to can see the result.

For a lung health check, keep the PDF or the link. The result is for your information, and may help you answer questions at your appointment. It does not decide whether you are offered a scan: the lung health check team asks its own questions and makes its own assessment.

Is anything I type stored?

No. Your answers stay in your browser while you use the calculator. If you download or email a PDF, they are used once to make it and are not kept. Your data explains what the site does and does not store.

What if I am worried about my health?

Pack years are a record of past smoking, not a diagnosis. They do not tell you whether you have a lung condition. If you are worried about your health, speak to your GP practice or use NHS 111. Free help to stop smoking is available: find NHS stop smoking support near you.