How this calculator works
CDAI uses seven daily observations, laboratory haematocrit and clinician-assessed complications. Count each complication category once over the week. The standard weight is supplied rather than inferred from an unverified ideal-weight table. This implementation preserves signed haematocrit and weight-deviation contributions in the original equation; some trial protocols apply additional conventions. CDAI is a clinical research activity index and can disagree with endoscopic inflammation. It is not a diagnostic test or a self-directed treatment plan. The result is an estimate for information only and is not medical advice.
Formula
CDAI = 2 x weekly liquid stools + 5 x weekly pain scores + 7 x weekly well-being scores + 20 x complication categories + 30 x antidiarrhoeal indicator + 10 x abdominal-mass code + 6 x (47 male or 42 female - haematocrit %) + 100 x (1 - current weight / standard weight).
Worked example
Seven liquid stools over the week with all other terms zero gives CDAI 14. If the weekly stool count is 14, pain total 7, well-being total 7, one complication, antidiarrhoeal use, no mass, a 2-point haematocrit deficit and 10% weight deficit, CDAI is 184.
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Frequently asked questions
Can I enter one day instead of a week?
No. Supply exactly seven daily counts or ratings; multiplying a single unusual day is unreliable.
Why ask for standard weight?
The original score uses percentage deviation from a reference weight. The reference should follow the clinical or trial protocol in use.
Does CDAI remission prove the bowel is healed?
No. Symptoms, biomarkers and endoscopic inflammation do not always agree.