How pipe smoking is counted

What counts as a bowl?

The calculator asks for bowls, not pipes or smoking sessions. Its help line says: “Count each bowl of tobacco you smoked. One bowl counts as 2½ cigarettes.” The original calculator labelled the same row “Pipe (no. of bowls)”.

The References page gives the figure as “One pipe (one bowl, or pipeful) is equivalent to 2½ cigarettes.” One pipe and one bowl mean the same thing.

Where does 2½ cigarettes come from?

It is one of the conversion figures taught at the National Respiratory Training Centre at Warwick, England. The original work behind these figures could not be found, but the authors kept them because large numbers of practice nurses had been trained using them. Two further sources, listed on the References page, were used to check that the figures were close to those of others working in this area.

How do I enter pipe smoking?

1. In the calculator, on “What have you smoked?”, tick Pipe, and anything else you smoked regularly.
2. The pipe step asks: “How many pipe bowls a day, and for how many years?”
3. Enter the number of bowls a day and the number of years. Use a decimal point for part years, for example 2.5.
4. If the number of bowls changed, choose Add another period and enter each amount with its own years.

If you smoked cigarettes or cigars as well, each type has its own step and the calculator adds them together. Entering a smoking history that changed explains periods and gaps.

After the tobacco steps, an optional history step asks whether you still smoke, when you stopped and how many years you smoked in total. FAQ 2 recommends recording stopping dates and years smoked alongside pack years.

What do 4 bowls a day for 30 years come to?

• 4 bowls × 2½ = 10 cigarettes a day.
• 10 × 30 years = 300.
• 300 ÷ 20 = 15 pack years.

At 4 bowls a day, each year adds half a pack year (10 ÷ 20). Someone who smoked 2 bowls a day and 15 cigarettes a day over the same 10 years would have 10 pack years: 2.5 from the pipe (2 × 2½ × 10 ÷ 20) and 7.5 from cigarettes (15 × 10 ÷ 20).

What happens after the result?

The result screen shows the total and a breakdown by type of tobacco. You can download or email a PDF, print the result, or save a link to it. Clinicians can also copy a line for the patient record.

What are the limits?

Every bowl counts the same, 2½ cigarettes; the calculator does not ask about the size of the pipe. The References page says: “This is not an exact science and approximations have been made.”

Pack years are a record of past smoking, not a diagnosis. If you are worried about your health, speak to your GP practice or use NHS 111. See how the calculation works for every conversion figure.