Bristol Stool Chart Explained

The Bristol Stool Scale (also called the Bristol Stool Chart) is a medical diagnostic tool designed to classify human stool into seven categories. Developed at the Bristol Royal Infirmary in 1997, it's now widely used by doctors and patients to communicate about digestive health in a standardized way.

The 7 Types

Type 1 — Separate hard lumps

Small, hard, separate lumps that are difficult to pass. This indicates severe constipation. Stool has spent too long in the colon, and too much water has been absorbed.

Type 2 — Lumpy and sausage-shaped

Sausage-shaped but lumpy. This also indicates constipation, though less severe than Type 1. The stool has been in the colon for an extended period.

Type 3 — Sausage with cracks

Like a sausage but with cracks on the surface. This is considered normal. It represents a healthy stool that has spent an appropriate amount of time in the colon.

Type 4 — Smooth and soft

Like a sausage or snake, smooth and soft. This is the ideal stool type. It's easy to pass and indicates optimal digestive function and transit time.

Type 5 — Soft blobs

Soft blobs with clear-cut edges, passed easily. This is on the border between normal and mild diarrhea. It may indicate a lack of fiber or slightly fast transit.

Type 6 — Mushy with ragged edges

Fluffy pieces with ragged edges, a mushy stool. This indicates mild diarrhea. Food may be moving through the digestive system too quickly.

Type 7 — Entirely liquid

Watery, no solid pieces, entirely liquid. This is severe diarrhea and can be a sign of infection, food intolerance, or other digestive conditions.

What's Normal?

Types 3 and 4 are generally considered ideal. They indicate that your digestive system is working well, with a healthy transit time and adequate water absorption.

Types 1-2 suggest constipation, while Types 5-7 indicate diarrhea. Persistent patterns at either extreme warrant a conversation with a healthcare provider.

Why Track Your Stool Type?

Stool consistency is one of the most reliable indicators of digestive health. Here's why tracking it matters:

• Identify patterns: You might notice that certain foods consistently push your stool type toward one extreme. This is valuable data for identifying food sensitivities.
• Monitor changes: During an elimination diet, stool type often shifts as you remove and reintroduce foods. Tracking helps you see these shifts objectively.
• Communicate with doctors: Using the Bristol Scale gives you a standardized way to describe your symptoms if you consult a gastroenterologist.
• Measure progress: As you identify and remove trigger foods, you should see your stool type trend toward the 3-4 range over time.

Factors That Affect Stool Type

Several factors beyond food can influence your stool consistency:

• Hydration: Not drinking enough water is one of the most common causes of constipation (Types 1-2).
• Fiber intake: Both too little and too much fiber can cause issues. Soluble fiber helps form stool, while insoluble fiber adds bulk.
• Stress: The gut-brain axis means that psychological stress can directly affect bowel function, often causing diarrhea.
• Physical activity: Regular exercise promotes healthy bowel motility and can help with constipation.
• Medications: Many medications have digestive side effects. Antibiotics in particular can disrupt the gut microbiome.
• Sleep: Poor sleep quality is associated with digestive issues and irregular bowel habits.

How EDSO Gut Guide Uses the Bristol Scale

In the EDSO Gut Guide app, you log your Bristol stool type as part of your daily symptom tracking. The app uses this data alongside your symptom severity scores to calculate a verdict for each food group you test during your elimination diet.

A significant shift in stool type during a food reintroduction phase — for example, moving from a consistent Type 4 during elimination to Type 6 during reintroduction — is a strong signal that the food may be a trigger for you.

Ready to start tracking? Sign up for early access to EDSO Gut Guide.