What is a normal CDAI score?

A CDAI under 150 is counted as clinical remission. Between 150 and 219 is mild, 220 to 449 moderate and 450 or more severe.

What CDAI score means remission?

Under 150 in current guidelines. The original 1976 paper put the line at 150 and below, so a score of exactly 150 sits on the boundary.

What counts as a CDAI response, 70 or 100 points?

A fall of 100 points or more is the usual definition of a clinical response. Some trials have used a 70-point fall instead, so check which definition a study or letter is using.

Can I calculate my CDAI at home?

You can calculate most of it from a 7-day diary. The abdominal mass needs an examination and the haematocrit needs a blood test, so a home score without them is a partial CDAI and should be labelled that way.

How do I add up a 7-day CDAI diary?

Each day, write down the number of liquid or very soft stools, a pain rating from 0 to 3 and a well-being rating from 0 to 4. After 7 days, add each column; those three totals are what the index multiplies by 2, 5 and 7.

What is the difference between the CDAI and the Harvey-Bradshaw Index?

The CDAI uses a 7-day diary, a blood test and weights for eight items. The Harvey-Bradshaw Index uses the previous day only, five unweighted items and no blood test; a total of 4 or less corresponds to a CDAI of 150 or less.

Why is the CDAI not used much in clinic?

It needs a week of diary data, a blood test and an examination, and different observers can reach quite different totals. It remains mainly a clinical trial measure; the Harvey-Bradshaw Index was designed as a simpler one-day version.

CDAI Calculator (Crohn's Disease Activity Index)

Work out your Crohn's Disease Activity Index from a 7-day diary.

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About 2 minutes
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Updated October 3, 2026

The short answer

The Crohn's Disease Activity Index (CDAI) adds eight weighted items: liquid or very soft stools over 7 days (x2), the 7-day sum of daily pain ratings (x5) and well-being ratings (x7), complications (x20 each), antidiarrhoeal use (x30), an abdominal mass (x10), the haematocrit shortfall (x6) and percent below standard weight (x1). Under 150 is clinical remission, 150 to 219 mild, 220 to 449 moderate and 450 or more severe. A drop of 100 points is the usual definition of a response.

Number of liquid or very soft stools over the last 7 daysAdd up each day's count of liquid or very soft stools for 7 days. For example 4, 3, 5, 2, 4, 3, 3 makes 24.

stools

Abdominal pain: the sum of your 7 daily ratingsRate each day 0 none, 1 mild, 2 moderate, 3 severe, then add the 7 ratings together (0 to 21).

General well-being: the sum of your 7 daily ratingsRate each day 0 generally well, 1 slightly under par, 2 poor, 3 very poor, 4 terrible, then add the 7 ratings together (0 to 28).

Which of these do you currently have?Each category scores 20 points, however many problems it contains. Tick only what a doctor has confirmed or what you have now.

Arthritis or joint pain (arthralgia)Iritis or uveitis (eye inflammation)Erythema nodosum, pyoderma gangrenosum or aphthous mouth ulcersAnal fissure, fistula or abscessAnother fistula (for example to the skin, bladder or vagina)Fever over 37.8°C (100°F) in the past week

In the last 7 days, did you take a medicine to slow diarrhoea, such as loperamide or diphenoxylate?

Abdominal massThis is judged by a clinician examining your abdomen. If nobody has checked, choose not examined, which scores 0 and makes this a partial score.

Sex used for the haematocrit referenceThe index expects a haematocrit of 47 in men and 42 in women. Only used if you enter a haematocrit below.

Haematocrit from a recent blood test, if you know itOptional. Enter it as a percentage, such as 40. If your report shows 0.40 L/L, that works too. Left blank, this item scores 0.

Your current weight, if you want the weight item includedOptional. Use the same unit as the standard weight below.

Your standard weight for your height, if your team has given you oneOptional. Trials take this from a height and sex table. Left blank, the weight item scores 0.

Your previous CDAI score, if you know itOptional. Used to show how much your score has changed.

How to use the CDAI Calculator

1Keep a 7-day diary: each day, count liquid or very soft stools and rate pain (0 to 3) and well-being (0 to 4).
2Add up each column and enter the three 7-day totals.
3Tick any complications, say whether you took an antidiarrhoeal, and choose the abdominal mass option (not examined unless a clinician has checked).
4Add your haematocrit and weight if you know them, then get your score, your band and a clear note of any item left at 0.

How the CDAI is scored

William Best and the National Cooperative Crohn's Disease Study group published the index in 1976. They recorded 18 candidate variables at 187 visits by 112 patients and used regression to find the eight that best predicted the physician's overall rating of how the patient was doing.

Each item is multiplied by a fixed weight and the products are added. The three diary items are sums over 7 days, so a single bad day moves the score far less than a bad week.

Item	How it is counted	Weight
Liquid or very soft stools	Total over 7 days	x2
Abdominal pain	Sum of 7 daily ratings: none 0, mild 1, moderate 2, severe 3	x5
General well-being	Sum of 7 daily ratings: generally well 0, slightly under par 1, poor 2, very poor 3, terrible 4	x7
Complications	Number of six categories present: arthritis or arthralgia; iritis or uveitis; erythema nodosum, pyoderma gangrenosum or aphthous stomatitis; anal fissure, fistula or abscess; other fistula; fever over 37.8°C in the past week	x20
Antidiarrhoeal use	Taken in the previous 7 days: no 0, yes 1	x30
Abdominal mass	None 0, questionable 2, definite 5 (clinician examination)	x10
Haematocrit	Men 47 minus haematocrit; women 42 minus haematocrit	x6
Body weight	Percent below standard weight	x1

What your score means

The original paper linked 150 and below with quiescent disease and values above 450 with extremely severe disease. Current guidelines use four bands, set out below. For change over time, a fall of 100 points is the most common definition of a clinical response, and some trials use 70.

This calculator scores any missing item as 0 and tells you which ones. If your haematocrit is below the expected value or you are under your standard weight, those items add points, so a partial score can read lower than a full one. Our guide to what a Harvey-Bradshaw score means explains how the shorter index maps onto these bands.

CDAI	Band
Under 150	Clinical remission
150 to 219	Mild
220 to 449	Moderate
450 or more	Severe
A fall of 100 or more	Usual definition of clinical response (some trials use 70)

What the score cannot tell you

It measures how you have felt, not what is happening in the bowel wall. In the SONIC trial, 72 of 136 people (53%) with a CDAI under 150 at week 26 had a healed lining on colonoscopy, and the authors concluded that half of those in clinical remission still had signs of active Crohn's.

The index is also known to vary between observers. When experienced clinicians scored the same patients, totals differed by tens and sometimes hundreds of points, and agreement improved when they first agreed on what terms such as liquid stool meant. That is why the score is best used to compare you with yourself, scored the same way each time. If your score and how you feel do not match, our guide to telling whether you are in a Crohn's flare covers the tests that settle it.

Frequently asked questions

What is a normal CDAI score?: A CDAI under 150 is counted as clinical remission. Between 150 and 219 is mild, 220 to 449 moderate and 450 or more severe.
What CDAI score means remission?: Under 150 in current guidelines. The original 1976 paper put the line at 150 and below, so a score of exactly 150 sits on the boundary.
What counts as a CDAI response, 70 or 100 points?: A fall of 100 points or more is the usual definition of a clinical response. Some trials have used a 70-point fall instead, so check which definition a study or letter is using.
Can I calculate my CDAI at home?: You can calculate most of it from a 7-day diary. The abdominal mass needs an examination and the haematocrit needs a blood test, so a home score without them is a partial CDAI and should be labelled that way.
How do I add up a 7-day CDAI diary?: Each day, write down the number of liquid or very soft stools, a pain rating from 0 to 3 and a well-being rating from 0 to 4. After 7 days, add each column; those three totals are what the index multiplies by 2, 5 and 7.
What is the difference between the CDAI and the Harvey-Bradshaw Index?: The CDAI uses a 7-day diary, a blood test and weights for eight items. The Harvey-Bradshaw Index uses the previous day only, five unweighted items and no blood test; a total of 4 or less corresponds to a CDAI of 150 or less.
Why is the CDAI not used much in clinic?: It needs a week of diary data, a blood test and an examination, and different observers can reach quite different totals. It remains mainly a clinical trial measure; the Harvey-Bradshaw Index was designed as a simpler one-day version.

Harvey-Bradshaw Index: What Your Score Means
Under 5 is remission, 5-7 mild, 8-16 moderate, above 16 severe. What the Harvey-Bradshaw Index measures, what it misses, and how to read your own score.
How to Tell If You're in a Crohn's Flare
Symptoms alone cannot confirm a Crohn's flare. How to read your own baseline, rule out the look-alikes, and use the tests that actually settle it.
What to Track in an IBD Symptom Diary
An IBD diary needs three layers: a daily symptom log, a dated event log for doses and steroids, and a treatment record that follows you. What goes in each.
High Calprotectin but No Symptoms: What It Means
A high faecal calprotectin while you feel fine usually means real inflammation you cannot feel, but not always. What the number means and what happens next.
Questions to Ask Your Doctor About Crohn's Disease
The questions that change what happens next in Crohn's care, what a useful answer sounds like, and how to fit them into a ten-minute appointment.

Sources

Best WR, Becktel JM, Singleton JW, Kern F Jr. Development of a Crohn's disease activity index. National Cooperative Crohn's Disease Study. Gastroenterology. 1976;70(3):439-44. doi:10.1016/S0016-5085(76)80163-1
Park JJ, Yang SK, Ye BD, Kim JW, Park DI, Yoon H, et al. Second Korean guidelines for the management of Crohn's disease. Intest Res. 2017;15(1):38-67. doi:10.5217/ir.2017.15.1.38
Freeman HJ. Use of the Crohn's disease activity index in clinical trials of biological agents. World J Gastroenterol. 2008;14(26):4127-30. doi:10.3748/wjg.14.4127
Vermeire S, Schreiber S, Sandborn WJ, Dubois C, Rutgeerts P. Correlation between the Crohn's disease activity and Harvey-Bradshaw indices in assessing Crohn's disease severity. Clin Gastroenterol Hepatol. 2010;8(4):357-63. doi:10.1016/j.cgh.2010.01.001
Peyrin-Biroulet L, Reinisch W, Colombel JF, Mantzaris GJ, Kornbluth A, Diamond R, et al. Clinical disease activity, C-reactive protein normalisation and mucosal healing in Crohn's disease in the SONIC trial. Gut. 2014;63(1):88-95. doi:10.1136/gutjnl-2013-304984

Cite this tool

Clairop. CDAI Calculator. www.clairop.com/tools/cdai-calculator. Updated October 3, 2026.

Clairop is a general wellness app for people living with a diagnosed digestive condition. It does not replace professional medical care, diagnosis, or treatment. Always follow your healthcare provider's advice.

Clairop logs meals, symptoms and stool in seconds, then looks for the foods your gut reacts to, including reactions that land days later.

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