Fatigue Severity Scale
Free online Fatigue Severity Scale calculator to assess fatigue severity. Answer 9 validated questions, get your FSS score from 1-7 with clinical significance interpretation and charts.
Read each statement carefully and choose a response that best describes your condition within the last week. Use the following scale:
1 = Strongly disagree | 2 = Disagree | 3 = Slightly disagree | 4 = Neither agree nor disagree | 5 = Slightly agree | 6 = Agree | 7 = Strongly agree
About This Calculator
About the Fatigue Severity Scale
The Fatigue Severity Scale (FSS) is a validated 9-item self-assessment questionnaire developed by Dr. Lauren Krupp and colleagues at the State University of New York at Stony Brook, first published in the Archives of Neurology in 1989. It is one of the most widely used instruments for measuring the severity of fatigue and its impact on daily functioning across various medical conditions, including multiple sclerosis, systemic lupus erythematosus, stroke, fibromyalgia, arthritis, and Parkinson's disease.
Fatigue affects a large proportion of patients with chronic illnesses — up to 90% of MS patients and 80% of SLE patients report clinically significant fatigue. The FSS helps clinicians and researchers quantify this symptom, track changes over time, and evaluate treatment effectiveness. Unlike simpler fatigue scales, the FSS specifically targets how fatigue interferes with physical, social, and occupational functioning.
How the Score Is Calculated
Each of the 9 FSS items is rated on a 7-point Likert scale from 1 (strongly disagree) to 7 (strongly agree). The final FSS score is the arithmetic mean of all 9 responses, ranging from 1 to 7. A score of 4 or higher is the widely accepted cutoff for clinically significant fatigue. For reference, healthy individuals typically score around 2.3, while patients with MS and SLE average 4.5–5.5. The FSS takes approximately 5–8 minutes to complete.
Regional Notes
India: The FSS is used by neurologists, rheumatologists, and rehabilitation specialists in India to assess fatigue in patients with MS, SLE, and post-stroke conditions. Major institutions such as the All India Institute of Medical Sciences (AIIMS) and Christian Medical College (CMC) use the FSS in clinical research and routine assessment. Chronic fatigue is a common complaint in Indian outpatient settings, and the FSS provides a standardized way to evaluate its severity.
United States: The National MS Society and the American College of Rheumatology recognize the FSS as a valid tool for fatigue assessment. It is widely used in US neurology and rheumatology clinics, as well as in clinical trials for fatigue-modifying therapies. The FSS is also employed by the US Department of Veterans Affairs for evaluating fatigue in veterans with chronic health conditions. A score of 4 or higher often triggers referral to occupational therapy or a fatigue management program.
United Kingdom: The National Institute for Health and Care Excellence (NICE) acknowledges the FSS as a recommended tool for assessing fatigue in neurological conditions. The NHS uses the FSS in MS care clinics, stroke rehabilitation services, and chronic fatigue syndrome assessment. In the UK, the FSS is often combined with other outcome measures like the Modified Fatigue Impact Scale (MFIS) for comprehensive fatigue evaluation.
Frequently Asked Questions
What is the Fatigue Severity Scale (FSS)?
The Fatigue Severity Scale (FSS) is a validated 9-item self-assessment questionnaire developed by Dr. Lauren Krupp and colleagues in 1989 to measure the severity of fatigue and its impact on daily functioning. It was originally designed for patients with multiple sclerosis and systemic lupus erythematosus but is now used across many patient populations including stroke, fibromyalgia, and arthritis.
How is the FSS score calculated and interpreted?
Each of the 9 FSS items is scored on a 7-point Likert scale from 1 (strongly disagree) to 7 (strongly agree). The final FSS score is the average of all 9 items, ranging from 1 to 7. A score of 4 or higher indicates clinically significant fatigue. Higher scores reflect a greater negative impact of fatigue on daily functioning. For example, healthy individuals typically average around 2.3, while those with clinically significant fatigue score 4 or above.
What conditions is the FSS used for?
The FSS is used to assess fatigue severity in multiple sclerosis (MS), systemic lupus erythematosus (SLE), stroke, fibromyalgia, arthritis, Parkinson's disease, chronic fatigue syndrome, and other medical conditions where fatigue is a prominent symptom. It helps clinicians evaluate the impact of fatigue on physical, social, and cognitive functioning and monitor treatment response over time.
What does a score of 2.3 indicate on the fatigue severity scale?
A FSS score of 2.3 is consistent with healthy individuals who do not experience clinically significant fatigue. Research by Grace and colleagues (2006) found that the average FSS score for healthy controls was 2.3. Scores below 4 generally indicate that fatigue is not having a clinically significant impact on daily functioning.
What does a score of 4 or higher on the FSS mean?
A FSS score of 4 or higher indicates clinically significant fatigue that may warrant medical evaluation. This threshold is widely accepted in research and clinical practice as indicating that fatigue is having a substantial negative impact on a person's daily functioning. If you score 4 or above, consider discussing your symptoms with a healthcare professional who can perform additional assessments.
Can I use the FSS for self-diagnosis?
No. The Fatigue Severity Scale is a screening tool, not a diagnostic instrument. It cannot replace a comprehensive medical evaluation by a qualified healthcare professional. If you are experiencing persistent fatigue that affects your quality of life, consult a doctor for proper assessment, diagnosis, and treatment. Additional evaluations may be needed to determine the underlying cause of your fatigue.
What are other fatigue assessment scales besides the FSS?
Other widely used fatigue assessment scales include the Brief Fatigue Inventory (BFI), the Modified Fatigue Impact Scale (MFIS), the Fatigue Numeric Rating Scale (NRS), the Visual Analog Fatigue Scale (VAFS), and the Functional Assessment of Chronic Illness Therapy — Fatigue (FACIT-F). Each scale has different strengths and is suited for different patient populations and clinical settings.
How long does it take to complete the FSS questionnaire?
The Fatigue Severity Scale takes approximately 5–8 minutes to complete. It consists of 9 simple statements about how fatigue affects your daily life, each rated on a 7-point scale. The quick administration time makes it a practical screening tool in both clinical settings and research studies across India, the United States, the United Kingdom, and worldwide.