Bowel movements

Bristol Stool Scale

Also called: Bristol stool chart, Bristol Stool Form Scale

The Bristol Stool Scale sorts stool into seven types based on shape and consistency. Types 3 and 4 are the healthy zone: smooth, sausage-shaped, easy to pass. Types 1 and 2 mean food is moving too slowly through the gut. Types 5 to 7 mean it is moving too quickly. Reading your stool is one of the cheapest health tools you have.

Where the scale came from

The Bristol Stool Scale was published by Dr Stephen Lewis and Dr Ken Heaton at the Bristol Royal Infirmary in 1997. It was designed as a simple visual tool to help patients describe their bowel habits without using vague words like normal or runny. It is now the standard reference in NHS gastroenterology clinics and most clinical research worldwide.

The seven types

  1. Separate hard lumps, like nuts. Hard to pass. Suggests stool has spent days in the colon.
  2. Sausage-shaped but lumpy. A few extra days of slow movement.
  3. Sausage-shaped with cracks on the surface. Healthy. Normal movement time.
  4. Smooth, soft sausage or snake. The ideal type.
  5. Soft blobs with clear-cut edges. Slightly fast movement, often after a high-fibre meal or coffee.
  6. Fluffy pieces with ragged edges, mushy. Mild diarrhoea. Gut irritated or moving fast.
  7. Watery, no solid pieces, entirely liquid. Severe diarrhoea. Gut moving everything through quickly.

Why type 4 is the goal

Smooth, sausage-shaped stool means food has spent the right amount of time in the colon. Long enough to absorb water properly, short enough that the stool has not dried out. It is the Goldilocks zone. Most clinicians aim for patients to spend most of their time at type 3 or 4.

How often is normal

Anywhere from three times a day to three times a week is within the normal range, as long as the form is healthy and consistent for you. The single best indicator of gut health is consistency in your own pattern, not absolute frequency.

When the scale flags something

The scale tells you when to ask questions, not what is wrong. NHS guidance is to see a GP if any of the following develop:

  • Blood in the stool, whether bright red, dark red or black and tarry.
  • A persistent change in bowel habit lasting more than three weeks.
  • A new and persistent change in stool shape, especially alongside other symptoms.
  • Pale, fatty, foul-smelling stool that floats, suggesting fat is not being absorbed.
  • Mucus in stool combined with pain or blood.

Common questions

What is type 4 on the Bristol Stool Scale?
Type 4 is the ideal: smooth, soft, sausage-shaped or snake-shaped, easy to pass without straining. It means the colon is reabsorbing the right amount of water and movement time is in the healthy range.
Is type 5 stool bad?
Type 5 is borderline. Slightly looser than ideal, often after a high-fibre or high-coffee day. If type 5 is your usual pattern and you feel fine, no problem. If it is a new shift toward looser stool that has held for more than two weeks, look for a recent food trigger or other change.
How long should it take to pass a stool?
A couple of minutes on the toilet at most. Gastroenterologists advise against sitting longer, and ongoing straining can point to constipation or pelvic floor issues. Phones in the bathroom have made the average toilet visit much longer than it should be.
Why does my stool look different every day?
Mild day-to-day variation is normal. What you ate, fluid intake, stress, sleep, and hormonal phase all affect movement time. Big swings between type 1 and type 7 from day to day are worth tracking, as alternating hard and loose stool can be linked to IBS. Two weeks of tracking can help reveal a trigger pattern.

Sources

The Book of Suna is general information, not medical advice. It is not a substitute for talking to a qualified healthcare professional about your own situation.