How this calculator works
The four time categories receive 3, 2, 1 and 0 points as the interval increases. The four daily-consumption categories receive 0, 1, 2 and 3 points as consumption increases. HSI adds these points. The 1989 study established the four-category coding; the 1991 FTND paper also describes the two-item index. A higher total reflects greater heaviness of smoking. This page does not attach later low, moderate or high bands to the original score, and does not translate other nicotine products into cigarettes. The result is an estimate for information only and is not medical advice.
Formula
HSI = time-to-first-cigarette points + daily-consumption points. Each component ranges from 0 to 3, giving a total from 0 to 6.
Worked example
Smoking the first cigarette 6 to 30 minutes after waking gives 2 points. Smoking 11 to 20 cigarettes per day adds 1, for HSI 3. Within 5 minutes and 31 or more cigarettes per day gives 6.
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Frequently asked questions
Can someone who does not smoke use HSI?
The original index concerns cigarette smokers. A non-smoker should not select the lowest categories and interpret zero as a validated non-smoker score.
How is HSI related to FTND?
HSI uses two behavioural components. The six-item FTND includes four additional questions and has a different total range.
Does a score of zero mean no health risk?
No. A low dependence score does not make cigarette smoking harmless or exclude a need for support.