HSI Calculator (Heaviness of Smoking Index, 0–6)

Understanding the Heaviness of Smoking Index calculator — concept and principle

The Heaviness of Smoking Index (HSI) is a two-question measure of nicotine dependence: how soon after waking you smoke and how many cigarettes you smoke a day. It takes seconds and is widely used in surveys, clinics and stop-smoking services.

Two questions only: with the default inputs the result is HSI 3 (medium dependence).

How it is calculated

HSI = points for time to first cigarette + points for cigarettes per day (0–6)

Time to first cigarette: within 5 min 3, 6–30 min 2, 31–60 min 1, after 60 min 0.
Cigarettes per day: 10 or fewer 0, 11–20 1, 21–30 2, 31 or more 3.
Bands: 0–1 low, 2–4 medium, 5–6 high dependence.

The principle

Researchers looking at the longer Fagerström questionnaire found that two items carried most of its information. Time to first cigarette reflects how strongly the body reacts to the overnight fall in nicotine. Daily cigarette count reflects the usual nicotine dose. Adding them gives a score that agrees well with the full six-question test while being much quicker.

Worked example

Default inputs: first cigarette 6–30 minutes after waking, 11–20 cigarettes a day.

Time points = 2.
Cigarettes points = 1.
HSI = 2 + 1 = 3 → Medium dependence.

How to read the result

Where does your result fall?

A low score suggests mild physical dependence; behavioural support alone may be enough for some. Medium and high scores suggest stronger withdrawal when quitting, where nicotine replacement or stop-smoking medicines combined with support usually improve success. The score does not measure motivation.

Common mistakes

Counting a rare unusual day rather than a typical one.
Using it for e-cigarettes or other tobacco products; it was designed for cigarettes.
Assuming a low score means quitting will be easy.

Keep in mind: This is a self-assessment, not a diagnosis. A doctor, pharmacist or stop-smoking service can help you choose support.

Frequently asked questions

What is the difference between HSI and the Fagerström test?

The Fagerström test has six questions; HSI keeps the two strongest ones.

Is time to first cigarette really that important?

Yes. Smoking within minutes of waking is one of the strongest single signs of dependence.

Does the HSI work for light smokers?

It separates them less well, because many score 0.

Sources: Heatherton TF, Kozlowski LT, Frecker RC, et al., "Measuring the heaviness of smoking: using self-reported time to the first cigarette of the day and number of cigarettes smoked per day", Br J Addict 1989;84:791–799 · NIDA Data Share, "Heaviness of Smoking Index (HSI)"

Checked 9 Nov 2026. Heatherton TF, Kozlowski LT, Frecker RC, et al., “Measuring the heaviness of smoking: using self-reported time to the first cigarette of the day and number of cigarettes smoked per day”, Br J Addict 1989; low / medium / high bands as listed by NIDA Data Share, “Heaviness of Smoking Index (HSI)”.

Your numbers