Bristol Stool Chart: Seven Types Explained
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What Is the Bristol Stool Chart?
The Bristol Stool Chart - also known as the Bristol Stool Scale or the Bristol Stool Form Scale - is a validated clinical classification tool that categorises human stool (faeces) into seven distinct types based on shape and consistency. It was developed at Bristol Royal Infirmary in 1997 by Dr Ken Heaton and Dr Stephen Lewis, and published in the Scandinavian Journal of Gastroenterology as "Stool Form Scale as a Useful Guide to Intestinal Transit Time".
The chart is widely used in NHS clinical practice as both a self-reporting tool for patients and an observational tool for clinicians. It is embedded in the Rome IV diagnostic criteria for Irritable Bowel Syndrome (IBS), which use Bristol types directly to subclassify IBS-C (constipation-predominant), IBS-D (diarrhoea-predominant), and IBS-M (mixed). NICE clinical guidelines also reference the chart when advising GPs on constipation and diarrhoea assessment.
The seven types represent a spectrum from the slowest transit (type 1, hard separate pellets) to the fastest (type 7, entirely liquid). Types 1 and 2 indicate constipation. Types 3 and 4 are normal, with type 4 considered the ideal. Types 5, 6, and 7 indicate loose stool or diarrhoea. Transit time - how long food takes to pass through the colon - is the primary driver of stool form.
The Seven Types at a Glance
| Type | Description | Meaning |
|---|---|---|
| 1 | Separate hard lumps | Constipation |
| 2 | Lumpy sausage | Constipation |
| 3 | Sausage with cracks | Low-end normal |
| 4 | Smooth sausage | Ideal |
| 5 | Soft blobs | Slightly loose |
| 6 | Fluffy pieces | Diarrhoea |
| 7 | Watery, no solid pieces | Severe diarrhoea |
How to Read the Scale
Slow colonic transit. Stool has lost too much water. Hard, difficult to pass. May require dietary change or laxative.
Healthy transit time. Type 4 is the gold standard. Soft, formed, passes easily without straining.
Fast transit. Stool has not had enough time in the colon. Type 7 is watery and may indicate acute illness.
The type you pass on any given day is influenced by your fibre and fluid intake, physical activity, stress, medications, and the health of your gut microbiome. Most people will see variation across types 3-5. Consistent type 1-2 or consistent type 6-7 warrants investigation if it persists for more than two to three weeks.
Why Type 4 Is the Goal
Type 4 is the universally agreed ideal stool form. A smooth, soft sausage shape with no cracks and no separate pieces indicates optimal colonic transit time, healthy hydration, and adequate fibre intake. Passing type 4 regularly is associated with comfortable, easy defecation without straining, and a reduced long-term risk of haemorrhoids, anal fissures, and diverticular disease.
Achieving consistent type 4 requires a combination of adequate fibre (aiming for the NHS adult target of 30g per day, though the UK average is only 18g), good hydration (1.5-2 litres of water per day), regular physical activity, and a consistent eating routine. The gut microbiome also plays a role: diverse gut bacteria support healthy fermentation of dietary fibre and normal bowel motility.
Read the full Type 4 guideWhen to Worry: Red Flag Symptoms
Most changes in stool consistency are benign and related to diet, hydration, or temporary illness. However, certain symptoms require prompt medical attention. According to NICE suspected-cancer referral guidance (NG12) and NHS guidance on bowel cancer, the following are red flags that warrant GP assessment, often on a 2-week-wait pathway:
Black or tarry stools (melaena) may indicate an upper gastrointestinal bleed and require same-day assessment or 999 if accompanied by dizziness or collapse.
Full Red Flags GuideUsing the Chart with IBS or IBD
The Bristol Stool Chart is embedded directly in the Rome IV diagnostic criteria for Irritable Bowel Syndrome. Clinicians use it to subclassify IBS:
- CIBS-C (constipation-predominant): more than 25% of stools are types 1 or 2, with fewer than 25% types 6 or 7.
- DIBS-D (diarrhoea-predominant): more than 25% of stools are types 6 or 7, with fewer than 25% types 1 or 2.
- MIBS-M (mixed): more than 25% each of types 1-2 AND types 6-7.
For IBD patients - those with Crohn's disease or ulcerative colitis - tracking Bristol types can help identify flare patterns before they escalate. A shift from type 4 to consistent type 6-7, especially with blood, mucus, urgency, or nocturnal symptoms, is a signal to contact your IBD clinical nurse specialist or GP.
Private Bowel Tracker - No Account Required
Our local-only bowel tracker lets you log your stool type, time, and optional notes. All data is stored exclusively in your browser's local storage - it never leaves your device, is never uploaded, and is never transmitted to any server. There is no account to create, no email address required, and no cloud synchronisation.
Tracking for two to four weeks before a GP appointment gives your doctor concrete data about your bowel pattern. You can export the full log as a CSV file to print or bring to an appointment. If you have IBS and are trying to confirm your subtype under Rome IV criteria, two weeks of consistent logging will tell you far more than a single consultation.