ISI scoring: calculate your total and understand the 0–28 bands
How do you calculate an ISI score?
Check that all seven items have one response scored from 0 to 4. Add those values once. There is no doubling step and no additional reverse-scoring when you use the printed ISI values.
A possible set of responses is 2, 3, 1, 2, 2, 1, 2. The calculation is 2 + 3 + 1 + 2 + 2 + 1 + 2 = 13. This fictional example falls in the 8–14 band.
A total below 0 or above 28 indicates a calculation or input problem. Check for duplicated items, omitted responses, or accidentally using a 1–5 numbering system.
What are the ISI score ranges?
These are the conventional interpretation bands. Some forms use clinical terminology in the labels; that wording does not turn a self-report total into a clinical assessment.
| Total | Conventional category |
|---|---|
| 0–7 | No clinically significant insomnia |
| 8–14 | Subthreshold insomnia |
| 15–21 | Clinical insomnia, moderate severity |
| 22–28 | Clinical insomnia, severe |
What does an ISI score of 7, 14, or 21 mean?
The endpoints belong to the band shown: 7 is in 0–7, 14 is in 8–14, and 21 is in 15–21. The next band starts at 8, 15, or 22 respectively.
Moving from 14 to 15 changes a category label, but that one point is not a sudden biological boundary. Read the individual answers and circumstances before interpreting a small difference as a major change.
Why do some sources use a cutoff of 10?
A screening cutoff and a severity band serve different purposes. Morin and colleagues found that 10 was an effective case-detection threshold in their community sample. That does not replace the conventional four-band description.
Consequently, a score of 12 can fall in the subthreshold severity band while exceeding a screening threshold used in a particular study. Those statements are compatible. Neither establishes a diagnosis for an individual.
Is my ISI score a percentage?
No. Dividing 14 by 28 does not mean a person has a 50% chance of insomnia, is losing half their sleep, or is functioning at half capacity. The total is a sum of responses on this questionnaire.
It is also not comparable point for point with PSS-10, GAD-7, or DASS-21. Each measure has its own content and interpretation. Avoid ranking your concerns simply by which test gives the largest number.
Does a low score mean I should ignore sleep problems?
No. A low total cannot rule out every sleep condition or explain persistent tiredness. You can seek advice because of the symptoms themselves, particularly if they interfere with your daily life.
When discussing a result, pair the number with a sentence: “My total was 6, but I keep falling asleep in class,” or “My total was 18 and I am worried about being awake for hours.” These are fictional examples of useful context, not diagnoses.
This page is educational. A questionnaire score cannot establish a diagnosis or explain the cause of your symptoms. If you are struggling, speak with a counselor or healthcare professional, whatever your score.
Read how to ask for support or find a helpline in your country.