Chalder Fatigue Scale (CFQ-11)
The 11-item fatigue questionnaire used across UK ME/CFS and long COVID services
The Chalder Fatigue Questionnaire was developed at King's College London and published by Trudie Chalder and colleagues in 1993. The 11-item version is the fatigue measure you are most likely to meet in UK research and in NHS ME/CFS and long COVID clinics; it was the primary outcome in the PACE trial and appears in most UK long COVID cohort studies. It asks about physical fatigue (7 items) and mental fatigue (4 items) over the past month, and if you have been tired for longer than that, compared with how you felt when you were last well.
It has two scoring systems, and this page gives you both. Likert scoring rates each answer 0–3 for a total of 0–33 and is the more sensitive to change. Bimodal scoring counts each item as either absent (0) or present (1) for a total of 0–11, with 4 or more the conventional threshold for clinically significant fatigue. Papers and clinic letters quote whichever they prefer, so it helps to know your score on both.
If your fatigue gets disproportionately worse after activity, the DSQ-PEM characterises that pattern specifically. The Fatigue Severity Scale measures the impact of fatigue on functioning rather than the symptom itself, and the FUNCAP profiles what activities cost you.
Your Chalder Fatigue Scale scores
Where your Likert score sits
Reference means from published cohorts, with your score marked.
Understanding your scores
Likert (0–33). In Cella and Chalder's 2010 study, 1,615 people from the UK community averaged 14.2 (SD 4.6) and 361 patients with chronic fatigue syndrome averaged 24.4 (SD 5.8). A score of 29 or more separated the two groups in 96% of cases. The PACE trial defined its "normal range" as 18 or below (the community mean plus one standard deviation) and treated a change of 2 points as clinically useful. Non-hospitalised long COVID cohorts have averaged around 15–16, with wide spread.
Bimodal (0–11). A score of 4 or more is the standard case threshold, from the original 1993 study (sensitivity 75.5%, specificity 74.5% against an interview measure of fatigue). Roughly one in seven people in general-population samples score 4 or more, so it is a screen for significant fatigue rather than a marker of any condition. CFS patients in the 2010 study averaged 9.1; the community sample averaged 3.3.
Subscales. The physical and mental subscales are usually reported separately in long COVID research, where mental fatigue items often stand out. Some 2023 long COVID trials have used 16 or more on physical and 8 or more on mental as markers of moderate-to-severe fatigue.
Because the recall period is a month, the scale suits monthly repeats during a treatment or pacing change. Note that the reference point ("compared with when you were last well") does not move, so a person who has been ill for years is still comparing against their healthy baseline.
This is not a diagnosis. Discuss your results with your doctor or specialist.