Bell CFIDS Disability Scale
Functional Capacity Rating 0–100
The Bell CFIDS Disability Scale is a functional capacity rating developed by Dr David Bell, a clinician and researcher who spent decades working with ME/CFS patients. It provides a single score from 0 to 100 that describes your overall level of functioning and activity limitation, where 100 represents no symptoms and full normal activity, and 0 represents severe symptoms with the patient bedridden and unable to care for themselves.
Unlike multi-item questionnaires, the Bell scale works by asking you to select the description that best matches your current level of functioning. This makes it very quick to complete and easy to understand. It is widely referenced in ME/CFS patient communities and advocacy literature, and is sometimes used informally alongside more formal instruments like the FSS.
The Bell scale is particularly useful as a simple, repeatable snapshot of functional status. Because it takes only a minute to complete, it lends itself to regular tracking. Many people with post-viral conditions use it weekly or monthly to maintain a record of their overall trajectory.
This is a free, interactive version. Select the description that best fits your current situation and see your score immediately. No sign-up or email is required.
Your Bell CFIDS Disability Scale score
Understanding your score
The Bell CFIDS Disability Scale runs from 0 to 100 in increments of 10. Each level has a specific description of symptom severity and functional capacity. Higher scores indicate better functioning.
The scale is most useful as a tracking tool. Noting your score at regular intervals gives you a record that can reveal gradual improvement or decline that might not be obvious day to day. A sustained shift of 10 or more points is generally considered meaningful.
This is a self-assessed measure of functional capacity. It is not a clinical diagnosis or measurement. Discuss your results with your doctor.