How do you calculate GAF?

Answer 1

Calculating the Global Assessment of Functioning (GAF)

1. Starting at the top level, evaluate each range by asking "is EITHER the individual's symptom or severity OR level of functioning worse than what is indicated in the range description?"

2. Keep moving down the scale until the range that best matches the individual's symptom severity OR the level of functioning is reached, WHICHEVER IS WORSE.

3. Look at the next lower range as a double-check against having stopped prematurely. This range should be too severe on BOTH symptom a severity AND level of functioning. If it is, the appropriate range has been reached (continue with step 4). If not, go back to step 2 and continue moving down the scale.

4. To determine the specific GAF rating within the selected 10-point range, consider whether the individual is functioning at the higher or lower end of the 10-point range. For example, consider an individual who hears voices that do not influence his behavior (e.g., someone with long-standing Schizophrenia who accepts his hallucinations as part of his illness). If the voices occur relatively infrequently (once a week or less), a rating of 39 or 40 might be most appropriate. In contrast, if the individual hears voices almost continuously, a rating of 31 or 32 would be more appropriate.


American Psychiatric Association. (2000). Multiaxial Assessment. Diagnostic and Statistical Manual of Mental Disorders.(Fourth Ed. text revision, p. 33). Washington, D.C.