Fatigue Severity Scale Calculator

Written by Great Medico

Updated September 25, 2026 •2 min read

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Fatigue can be difficult to quantify because it affects motivation, activity and daily roles at the same time. The Fatigue Severity Scale (FSS) turns nine statements into an average score that describes how strongly fatigue is affecting life.

What this calculator does

Each of the nine FSS statements is rated from 1 to 7, from strong disagreement to strong agreement. The calculator shows the total out of 63 and the average out of 7. The questions focus on fatigue’s effect on physical functioning, duties, work, family and social life.

How to use it

Choose the response that best reflects your recent experience using the timeframe intended by your clinician or the questionnaire you were given. Answer all nine items; leaving out statements changes the meaning of the average. Try not to rate only your single worst day.

How the calculation works

The engine sums Q1 through Q9 and divides by 9. A total of 36 points, for example, produces an average of 4.0. This implementation labels an average above 4 as a clinically significant fatigue range and scores of 4 or below as below that common cutoff.

Example

The default example gives 1 point to every statement. The total is therefore 9/63 and the mean is 1/7, which falls below the common significant-fatigue threshold. Higher agreement across several items raises the average.

How to interpret the result

The FSS measures perceived fatigue severity and functional impact; it does not identify the cause. A high score can occur with neurologic disease, sleep problems, anemia, infection, medication effects, mood disorders and many other conditions, so interpretation belongs in the wider clinical picture.

Limitations and notes

Cutoffs vary by population and study, and a single number should not be used to diagnose a disease or disability. If fatigue is new, severe, worsening, or associated with symptoms such as chest pain, breathlessness, fainting, fever or significant weakness, seek appropriate medical evaluation.