The FSS was developed in 1989 for multiple sclerosis and lupus and is now used in many conditions, including long COVID and chronic fatigue syndrome. An average score of 4 or more (total 36 or more) suggests problematic fatigue.
How to use the Fatigue Severity Scale Calculator
- 1. My motivation is lower when I am fatigued (1 strongly disagree – 7 strongly agree)
- 2. Exercise brings on my fatigue (1 strongly disagree – 7 strongly agree)
- 3. I am easily fatigued (1 strongly disagree – 7 strongly agree)
- 4. Fatigue interferes with my physical functioning (1 strongly disagree – 7 strongly agree)
- 5. Fatigue causes frequent problems for me (1 strongly disagree – 7 strongly agree)
- 6. My fatigue prevents sustained physical functioning (1 strongly disagree – 7 strongly agree)
- 7. Fatigue interferes with carrying out certain duties and responsibilities (1 strongly disagree – 7 strongly agree)
- 8. Fatigue is among my three most disabling symptoms (1 strongly disagree – 7 strongly agree)
- 9. Fatigue interferes with my work, family or social life (1 strongly disagree – 7 strongly agree)
Results update as you type, and every field accepts the units shown in its menu.
How it works
Each answer carries the points shown in the published score. The calculator adds them up and maps the total to the published interpretation.
Inputs explained
| Field | What to enter |
|---|---|
| 1. My motivation is lower when I am fatigued (1 strongly disagree – 7 strongly agree) | A number |
| 2. Exercise brings on my fatigue (1 strongly disagree – 7 strongly agree) | A number |
| 3. I am easily fatigued (1 strongly disagree – 7 strongly agree) | A number |
| 4. Fatigue interferes with my physical functioning (1 strongly disagree – 7 strongly agree) | A number |
| 5. Fatigue causes frequent problems for me (1 strongly disagree – 7 strongly agree) | A number |
| 6. My fatigue prevents sustained physical functioning (1 strongly disagree – 7 strongly agree) | A number |
| 7. Fatigue interferes with carrying out certain duties and responsibilities (1 strongly disagree – 7 strongly agree) | A number |
| 8. Fatigue is among my three most disabling symptoms (1 strongly disagree – 7 strongly agree) | A number |
| 9. Fatigue interferes with my work, family or social life (1 strongly disagree – 7 strongly agree) | A number |
What each result means
- Mean FSS score = ([1. My motivation is lower when I am fatigued (1 strongly disagree – 7 strongly agree)] + [2. Exercise brings on my fatigue (1 strongly disagree – 7 strongly agree)] + [3. I am easily fatigued (1 strongly disagree – 7 strongly agree)] + [4. Fatigue interferes with my physical functioning (1 strongly disagree – 7 strongly agree)] + [5. Fatigue causes frequent problems for me (1 strongly disagree – 7 strongly agree)] + [6. My fatigue prevents sustained physical functioning (1 strongly disagree – 7 strongly agree)] + [7. Fatigue interferes with carrying out certain duties and responsibilities (1 strongly disagree – 7 strongly agree)] + [8. Fatigue is among my three most disabling symptoms (1 strongly disagree – 7 strongly agree)] + [9. Fatigue interferes with my work, family or social life (1 strongly disagree – 7 strongly agree)])÷9
- Total score = [1. My motivation is lower when I am fatigued (1 strongly disagree – 7 strongly agree)] + [2. Exercise brings on my fatigue (1 strongly disagree – 7 strongly agree)] + [3. I am easily fatigued (1 strongly disagree – 7 strongly agree)] + [4. Fatigue interferes with my physical functioning (1 strongly disagree – 7 strongly agree)] + [5. Fatigue causes frequent problems for me (1 strongly disagree – 7 strongly agree)] + [6. My fatigue prevents sustained physical functioning (1 strongly disagree – 7 strongly agree)] + [7. Fatigue interferes with carrying out certain duties and responsibilities (1 strongly disagree – 7 strongly agree)] + [8. Fatigue is among my three most disabling symptoms (1 strongly disagree – 7 strongly agree)] + [9. Fatigue interferes with my work, family or social life (1 strongly disagree – 7 strongly agree)]
Example values
How the main result changes when 1. My motivation is lower when I am fatigued changes and everything else stays at the example values above:
| 1. My motivation is lower when I am fatigued (1 strongly disagree – 7 strongly agree) | Mean FSS score |
|---|---|
| 2 | 3.78 |
| 3 | 3.89 |
| 4 | 4 |
| 5 | 4.11 |
| 6 | 4.22 |
Health note: this calculator is for education and screening only and is not a diagnosis or treatment advice. Discuss your results with a qualified clinician.
Formula
Score = sum of the points for each item
Worked example
Inputs — 1. My motivation is lower when I am fatigued (1 strongly disagree – 7 strongly agree): 4; 2. Exercise brings on my fatigue (1 strongly disagree – 7 strongly agree): 4; 3. I am easily fatigued (1 strongly disagree – 7 strongly agree): 4; 4. Fatigue interferes with my physical functioning (1 strongly disagree – 7 strongly agree): 4; 5. Fatigue causes frequent problems for me (1 strongly disagree – 7 strongly agree): 4; 6. My fatigue prevents sustained physical functioning (1 strongly disagree – 7 strongly agree): 4; 7. Fatigue interferes with carrying out certain duties and responsibilities (1 strongly disagree – 7 strongly agree): 4; 8. Fatigue is among my three most disabling symptoms (1 strongly disagree – 7 strongly agree): 4; 9. Fatigue interferes with my work, family or social life (1 strongly disagree – 7 strongly agree): 4.
Results — Mean FSS score = 4; Total score = 36 / 63.
Key terms
- FSS
- Fatigue Severity Scale.
Frequently asked questions
What FSS score means significant fatigue?
An average of 4 or more.
Which period should I think about?
The past week.
What can cause fatigue?
Sleep problems, anaemia, thyroid disease, depression, medicines and many chronic illnesses.